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Azevedo MD, Prince N, Humbert-Claude M, Mesa-Infante V, Jeanneret C, Golzne V, De Matos K, Jamot BB, Magara F, Gonzalez-Hernandez T, Tenenbaum L. Oxidative stress induced by sustained supraphysiological intrastriatal GDNF delivery is prevented by dose regulation. Mol Ther Methods Clin Dev 2023; 31:101106. [PMID: 37766790 PMCID: PMC10520444 DOI: 10.1016/j.omtm.2023.09.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 09/06/2023] [Indexed: 09/29/2023]
Abstract
Despite its established neuroprotective effect on dopaminergic neurons and encouraging phase I results, intraputaminal GDNF administration failed to demonstrate significant clinical benefits in Parkinson's disease patients. Different human GDNF doses were delivered in the striatum of rats with a progressive 6-hydroxydopamine lesion using a sensitive doxycycline-regulated AAV vector. GDNF treatment was applied either continuously or intermittently (2 weeks on/2 weeks off) during 17 weeks. Stable reduction of motor impairments as well as increased number of dopaminergic neurons and striatal innervation were obtained with a GDNF dose equivalent to 3- and 10-fold the rat endogenous level. In contrast, a 20-fold increased GDNF level only temporarily provided motor benefits and neurons were not spared. Strikingly, oxidized DNA in the substantia nigra increased by 50% with 20-fold, but not 3-fold GDNF treatment. In addition, only low-dose GDNF allowed to preserve dopaminergic neuron cell size. Finally, aberrant dopaminergic fiber sprouting was observed with 20-fold GDNF but not at lower doses. Intermittent 20-fold GDNF treatment allowed to avoid toxicity and spare dopaminergic neurons but did not restore their cell size. Our data suggest that maintaining GDNF concentration under a threshold generating oxidative stress is a pre-requisite to obtain significant symptomatic relief and neuroprotection.
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Affiliation(s)
- Marcelo Duarte Azevedo
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Naika Prince
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Marie Humbert-Claude
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Virginia Mesa-Infante
- Departamento de Ciencias Médicas Básicas, Facultad de Ciencias de la Salud, Instituto de Tecnologías Biomédicas (ITB), Universidad de La Laguna, La Laguna, 38200 Tenerife, Spain
| | - Cheryl Jeanneret
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Valentine Golzne
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Kevin De Matos
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
| | - Benjamin Boury Jamot
- Center for the Study of Behaviour, Department of Psychiatry, Lausanne University Hospital and University of Lausanne (CHUV-UNIL), 1008 Lausanne, Switzerland
| | - Fulvio Magara
- Center for the Study of Behaviour, Department of Psychiatry, Lausanne University Hospital and University of Lausanne (CHUV-UNIL), 1008 Lausanne, Switzerland
| | - Tomas Gonzalez-Hernandez
- Departamento de Ciencias Médicas Básicas, Facultad de Ciencias de la Salud, Instituto de Tecnologías Biomédicas (ITB), Universidad de La Laguna, La Laguna, 38200 Tenerife, Spain
| | - Liliane Tenenbaum
- Laboratory of Cellular and Molecular Neurotherapies, Center for Neuroscience Research, Clinical Neurosciences Department, Lausanne University Hospital (CHUV) and University of Lausanne (UNIL), 1011 Lausanne, Switzerland
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2
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Toutounchian S, Ahmadbeigi N, Mansouri V. Retinal and Choroidal Neovascularization Antivascular Endothelial Growth Factor Treatments: The Role of Gene Therapy. J Ocul Pharmacol Ther 2022; 38:529-548. [PMID: 36125411 DOI: 10.1089/jop.2022.0022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Neovascularization in ocular vessels causes a major disease burden. The most common causes of choroidal neovascularization (CNV) are age-related macular degeneration and diabetic retinopathy, which are the leading causes of irreversible vision loss in the adult population. Vascular endothelial growth factor (VEGF) is critical for the formation of new vessels and is the main regulator in ocular angiogenesis and vascular permeability through its receptors. Laser therapy and antiangiogenic factors have been used for CNV treatment. Bevacizumab, ranibizumab, and aflibercept are commonly used anti-VEGF agents; however, high costs and the need for frequent intraocular injections are major drawbacks of anti-VEGF drugs. Gene therapy, given the potency of one-time treatment and no need for frequent injections offers the real possibility of such a lasting treatment, with fewer adverse effects and higher patient quality of life. Herein, we reviewed the role of gene therapy in the CNV treatment. In addition, we discuss the advantages and challenges of current treatments compared with gene therapy.
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Affiliation(s)
- Samaneh Toutounchian
- Gene Therapy Research Center, Digestive Diseases Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Naser Ahmadbeigi
- Gene Therapy Research Center, Digestive Diseases Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
| | - Vahid Mansouri
- Gene Therapy Research Center, Digestive Diseases Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran
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Peng H, Ramadurgum P, Woodard DR, Daniel S, Nakahara E, Renwick M, Aredo B, Datta S, Chen B, Ufret-Vincenty R, Hulleman JD. Utility of the DHFR-based destabilizing domain across mouse models of retinal degeneration and aging. iScience 2022; 25:104206. [PMID: 35521529 PMCID: PMC9062244 DOI: 10.1016/j.isci.2022.104206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Revised: 02/16/2022] [Accepted: 04/04/2022] [Indexed: 11/25/2022] Open
Abstract
The Escherichia coli dihydrofolate reductase (DHFR) destabilizing domain (DD) serves as a promising approach to conditionally regulate protein abundance in a variety of tissues. To test whether this approach could be effectively applied to a wide variety of aged and disease-related ocular mouse models, we evaluated the DHFR DD system in the eyes of aged mice (up to 24 months), a light-induced retinal degeneration (LIRD) model, and two genetic models of retinal degeneration (rd2 and Abca4−/− mice). The DHFR DD was effectively degraded in all model systems, including rd2 mice, which showed significant defects in chymotrypsin proteasomal activity. Moreover, trimethoprim (TMP) administration stabilized the DHFR DD in all mouse models. Thus, the DHFR DD-based approach allows for control of protein abundance in a variety of mouse models, laying the foundation to use this strategy for the conditional control of gene therapies to potentially treat multiple eye diseases. Destabilizing domains (DDs) confer conditional control of ocular protein abundance The DHFR DD is effectively turned over and stabilized in aged mouse’s retina DHFR DDs perform well in environmental and genetic retinal degenerative models
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4
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Regulation of protein secretion through chemical regulation of endoplasmic reticulum retention signal cleavage. Nat Commun 2022; 13:1323. [PMID: 35260576 PMCID: PMC8904541 DOI: 10.1038/s41467-022-28971-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Accepted: 02/23/2022] [Indexed: 12/12/2022] Open
Abstract
Secreted proteins, such as hormones or cytokines, are key mediators in multicellular organisms. Response of protein secretion based on transcriptional control is rather slow, as it requires transcription, translation and transport from the endoplasmic reticulum (ER) to the plasma membrane via the conventional protein secretion (CPS) pathway. An alternative regulation to provide faster response would be valuable. Here we present two genetically encoded orthogonal regulatory secretion systems, which rely on the retention of pre-synthesized proteins on the ER membrane (membER, released by a cytosolic protease) or inside the ER lumen (lumER, released by an ER-luminal protease), respectively, and their release by the chemical signal-regulated proteolytic removal of an ER-retention signal, without triggering ER stress due to protein aggregates. Design of orthogonal chemically-regulated split proteases enables the combination of signals into logic functions. Its application was demonstrated on a chemically regulated therapeutic protein secretion and regulated membrane translocation of a chimeric antigen receptor (CAR) targeting cancer antigen. Regulation of the ER escape represents a platform for the design of fast-responsive and tightly-controlled modular and scalable protein secretion system for mammalian cells. Secreted proteins, such as hormones or cytokines, are key mediators in multicellular organisms. Here the authors present two genetically encoded orthogonal regulatory secretion systems that enables inducible protein release and construction of logic gates.
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Tornabene P, Trapani I, Centrulo M, Marrocco E, Minopoli R, Lupo M, Iodice C, Gesualdo C, Simonelli F, Surace EM, Auricchio A. Inclusion of a degron reduces levelsof undesired inteins after AAV-mediated protein trans-splicing in the retina. Mol Ther Methods Clin Dev 2021; 23:448-459. [PMID: 34786437 PMCID: PMC8571531 DOI: 10.1016/j.omtm.2021.10.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 10/01/2021] [Accepted: 10/11/2021] [Indexed: 12/02/2022]
Abstract
Split intein-mediated protein trans-splicing expands AAV transfer capacity, thus overcoming the limited AAV cargo. However, non-mammalian inteins persist as trans-splicing by-products, and this could raise safety concerns for AAV intein clinical applications. In this study, we tested the ability of several degrons to selectively decrease levels of inteins after protein trans-splicing and found that a version of E. coli dihydrofolate reductase, which we have shortened to better fit into the AAV vector, is the most effective. We show that subretinal administration of AAV intein armed with this short degron is both safe and effective in a mouse model of Stargardt disease (STGD1), which is the most common form of inherited macular degeneration in humans. This supports the use of optimized AAV intein for gene therapy of both STGD1 and other conditions that require transfer of large genes.
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Affiliation(s)
- Patrizia Tornabene
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Ivana Trapani
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
- Medical Genetics, Department of Translational Medicine, Federico II University, Naples 80131, Italy
| | - Miriam Centrulo
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Elena Marrocco
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Renato Minopoli
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Mariangela Lupo
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Carolina Iodice
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
| | - Carlo Gesualdo
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania L. Vanvitelli, Naples 80131, Italy
| | - Francesca Simonelli
- Eye Clinic, Multidisciplinary Department of Medical, Surgical and Dental Sciences, University of Campania L. Vanvitelli, Naples 80131, Italy
| | - Enrico M. Surace
- Medical Genetics, Department of Translational Medicine, Federico II University, Naples 80131, Italy
| | - Alberto Auricchio
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy
- Medical Genetics, Department of Advanced Biomedicine, Federico II University, Naples 80131, Italy
- Correspondence: Alberto Auricchio, MD, Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli 80078, Italy; Medical Genetics, Department of Translational Medicine, Federico II University, Naples 80131, Italy.
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6
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Sinnett SE, Boyle E, Lyons C, Gray SJ. Engineered microRNA-based regulatory element permits safe high-dose miniMECP2 gene therapy in Rett mice. Brain 2021; 144:3005-3019. [PMID: 33950254 DOI: 10.1093/brain/awab182] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 04/23/2021] [Accepted: 04/26/2021] [Indexed: 11/12/2022] Open
Abstract
MECP2 gene transfer has been shown to extend the survival of Mecp2-/y knockout (KO) mice modeling Rett syndrome (RTT), an X-linked neurodevelopmental disorder. However, controlling deleterious overexpression of MeCP2 remains the critical unmet obstacle towards a safe and effective gene therapy approach for RTT. A recently developed truncated miniMECP2 gene has also been shown to be therapeutic after AAV9-mediated gene transfer in KO neonates. We show that AAV9/miniMECP2 has a similar dose-dependent toxicity profile to that of a published second-generation AAV9/MECP2 vector after treatment in adolescent mice. To overcome that toxicity, we developed a risk-driven viral genome design strategy rooted in high-throughput profiling and genome mining to rationally develop a compact, synthetic miRNA target panel (miR-Responsive Auto-Regulatory Element, "miRARE") to minimize the possibility of miniMECP2 transgene overexpression in the context of RTT gene therapy. The goal of miRARE is to have a built-in inhibitory element responsive to MeCP2 overexpression. The data provided herein show that insertion of miRARE into the miniMECP2 gene expression cassette greatly improved the safety of miniMECP2 gene transfer without compromising efficacy. Importantly, this built-in regulation system does not require any additional exogenous drug application, and no miRNAs are expressed from the transgene cassette. Although broad applications of miRARE have yet to be determined, the design of miRARE suggests a potential use in gene therapy approaches for other dose-sensitive genes.
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Affiliation(s)
- Sarah E Sinnett
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.,Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Emily Boyle
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Christopher Lyons
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Steven J Gray
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.,Eugene McDermott Center for Human Growth and Development, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
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Ramadurgum P, Daniel S, Hulleman JD. Protocol for In Vivo Evaluation and Use of Destabilizing Domains in the Eye, Liver, and Beyond. STAR Protoc 2020; 1. [PMID: 32995756 PMCID: PMC7521670 DOI: 10.1016/j.xpro.2020.100094] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Destabilizing domains (DDs) have been used successfully to conditionally control the abundance of proteins of interest (POIs) in a small-molecule-dependent manner in mice, worms (Caenorhabditis elegans), and Drosophila. However, development of such systems must account for delivery of the DD-POIs to the target tissue, accessibility of the target tissue to the small molecule, and quantification of stabilization. Here, we describe the considerations and steps to take in order to effectively implement a DD-POI in mouse ocular and hepatic tissue. For complete details on the use and execution of this protocol, please refer to Datta et al. (2018), Ramadurgum and Hulleman (2020), and Ramadurgum et al. (2020).
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Affiliation(s)
- Prerana Ramadurgum
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
| | - Steffi Daniel
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA
| | - John D Hulleman
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA.,Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA.,Technical Contact
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8
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Ramadurgum P, Hulleman JD. Protocol for Designing Small-Molecule-Regulated Destabilizing Domains for In Vitro Use. STAR Protoc 2020; 1. [PMID: 32995752 PMCID: PMC7521665 DOI: 10.1016/j.xpro.2020.100069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The use of destabilizing domains (DDs) to conditionally control the abundance of a protein of interest (POI) through a small-molecule stabilizer has gained increasing traction both in vitro and in vivo. Yet there are specific considerations for the development and accurate control of user-defined POIs via DDs, as well as the identification of novel (and potentially synergistic) small-molecule stabilizers. Here, we describe a platform for achieving these goals. For complete details on the use and execution of this protocol, please refer to Ramadurgum et al. (2020). Conditional protein of interest (POI) regulation by destabilizing domain (DD) fusion Focus on the utility of the E. coli dihydrofolate reductase (ecDHFR) DD Dynamically define the levels of a POI through diverse ligands Simultaneous DD stabilization and control of synergistic cellular signaling pathways
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Affiliation(s)
- Prerana Ramadurgum
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - John D Hulleman
- Department of Ophthalmology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.,Department of Pharmacology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA.,Technical Contact.,Lead Contact
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Di Maria V, Moindrot M, Ryde M, Bono A, Quintino L, Ledri M. Development and Validation of CRISPR Activator Systems for Overexpression of CB1 Receptors in Neurons. Front Mol Neurosci 2020; 13:168. [PMID: 33013319 PMCID: PMC7506083 DOI: 10.3389/fnmol.2020.00168] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 08/11/2020] [Indexed: 01/02/2023] Open
Abstract
Gene therapy approaches using viral vectors for the overexpression of target genes have been for several years the focus of gene therapy research against neurological disorders. These approaches deliver robust expression of therapeutic genes, but are typically limited to the delivery of single genes and often do not manipulate the expression of the endogenous locus. In the last years, the advent of CRISPR-Cas9 technologies have revolutionized many areas of scientific research by providing novel tools that allow simple and efficient manipulation of endogenous genes. One of the applications of CRISPR-Cas9, termed CRISPRa, based on the use of a nuclease-null Cas9 protein (dCas9) fused to transcriptional activators, enables quick and efficient increase in target endogenous gene expression. CRISPRa approaches are varied, and different alternatives exist with regards to the type of Cas9 protein and transcriptional activator used. Several of these approaches have been successfully used in neurons in vitro and in vivo, but have not been so far extensively applied for the overexpression of genes involved in synaptic transmission. Here we describe the development and application of two different CRISPRa systems, based on single or dual Lentiviral and Adeno-Associated viral vectors and VP64 or VPR transcriptional activators, and demonstrate their efficiency in increasing mRNA and protein expression of the Cnr1 gene, coding for neuronal CB1 receptors. Both approaches were similarly efficient in primary neuronal cultures, and achieved a 2–5-fold increase in Cnr1 expression, but the AAV-based approach was more efficient in vivo. Our dual AAV-based VPR system in particular, based on Staphylococcus aureus dCas9, when injected in the hippocampus, displayed almost complete simultaneous expression of both vectors, high levels of dCas9 expression, and good efficiency in increasing Cnr1 mRNA as measured by in situ hybridization. In addition, we also show significant upregulation of CB1 receptor protein in vivo, which is reflected by an increased ability in reducing neurotransmitter release, as measured by electrophysiology. Our results show that CRISPRa techniques could be successfully used in neurons to target overexpression of genes involved in synaptic transmission, and can potentially represent a next-generation gene therapy approach against neurological disorders.
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Affiliation(s)
- Valentina Di Maria
- Laboratory of Molecular Neurophysiology and Epilepsy, Department of Clinical Sciences, Epilepsy Center, Lund University, Lund, Sweden
| | - Marine Moindrot
- Laboratory of Molecular Neurophysiology and Epilepsy, Department of Clinical Sciences, Epilepsy Center, Lund University, Lund, Sweden
| | - Martin Ryde
- Laboratory of Molecular Neurophysiology and Epilepsy, Department of Clinical Sciences, Epilepsy Center, Lund University, Lund, Sweden
| | - Antonino Bono
- Laboratory of Molecular Neurophysiology and Epilepsy, Department of Clinical Sciences, Epilepsy Center, Lund University, Lund, Sweden
| | - Luis Quintino
- Laboratory of CNS Gene Therapy, Department of Experimental Medical Sciences, Lund University, Lund, Sweden
| | - Marco Ledri
- Laboratory of Molecular Neurophysiology and Epilepsy, Department of Clinical Sciences, Epilepsy Center, Lund University, Lund, Sweden
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Abstract
PURPOSE OF REVIEW Diabetic retinopathy (DR), a leading cause of visual impairment in the developed country, is characterized by vascular lesions and neuronal damage of the retina. Treatment options for this condition are currently limited. The advent of therapy targeting vascular endothelial growth factor (VEGF) demonstrated significant benefits to patients with DR. However, this treatment is limited by its short half-life and requirement for frequent invasive intravitreal injections. In addition, many patients failed to achieve clinically significant improvement in visual function. Gene therapy has the potential to provide an alternative treatment for DR with distinct advantages, such as longer therapeutic effect, less injection frequency, ability to intervene at disease onset, and potentially fewer side effects. RECENT FINDINGS Strategies for gene therapy in DR, stemming from the current understanding of the disease pathogenesis, focus on the inhibition of neovascularization and protection of neurovascular degeneration in the retina. Studies with promising results have mainly focussed on animal models due to efficacy and safety concerns, despite a number of successful preclinical studies using adeno-associated virus-mediated transduction to treat both vascular dysfunction and neuronal degeneration. With the optimization of delivery vectors, transgene regulation, and outcome measure, gene therapy will potentially become available for patients with DR. This review provides an update on the current strategies utilized in DR gene therapy research. Several barriers to the clinical application of gene therapy for DR are highlighted, and future directions for this research are proposed.
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Affiliation(s)
- Jiang-Hui Wang
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Georgina Eloise Roberts
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Australia
| | - Guei-Sheung Liu
- Menzies Institute for Medical Research, University of Tasmania, 17 Liverpool Street, Hobart, TAS, 7000, Australia.
- Ophthalmology, Department of Surgery, University of Melbourne, East Melbourne, Australia.
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Simultaneous Control of Endogenous and User-Defined Genetic Pathways Using Unique ecDHFR Pharmacological Chaperones. Cell Chem Biol 2020; 27:622-634.e6. [PMID: 32330442 DOI: 10.1016/j.chembiol.2020.03.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/04/2020] [Accepted: 03/06/2020] [Indexed: 12/12/2022]
Abstract
Destabilizing domains (DDs), such as a mutated form of Escherichia coli dihydrofolate reductase (ecDHFR), confer instability and promote protein degradation. However, when combined with small-molecule stabilizers (e.g., the antibiotic trimethoprim), DDs allow positive regulation of fusion protein abundance. Using a combinatorial screening approach, we identified and validated 17 unique 2,4-diaminopyrimidine/triazine-based ecDHFR DD stabilizers, at least 15 of which were ineffective antibiotics against E. coli and S. aureus. Identified stabilizers functioned in vivo to control an ecDHFR DD-firefly luciferase in the mouse eye and/or the liver. Next, stabilizers were leveraged to perform synergistic dual functions in vitro (HeLa cell death sensitization) and in vivo (repression of ocular inflammation) by stabilizing a user-defined ecDHFR DD while also controlling endogenous signaling pathways. Thus, these newly identified pharmacological chaperones allow for simultaneous control of compound-specific endogenous and user-defined genetic pathways, the combination of which may provide synergistic effects in complex biological scenarios.
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12
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Duarte Azevedo M, Sander S, Tenenbaum L. GDNF, A Neuron-Derived Factor Upregulated in Glial Cells during Disease. J Clin Med 2020; 9:jcm9020456. [PMID: 32046031 PMCID: PMC7073520 DOI: 10.3390/jcm9020456] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 01/31/2020] [Accepted: 02/03/2020] [Indexed: 12/20/2022] Open
Abstract
In a healthy adult brain, glial cell line-derived neurotrophic factor (GDNF) is exclusively expressed by neurons, and, in some instances, it has also been shown to derive from a single neuronal subpopulation. Secreted GDNF acts in a paracrine fashion by forming a complex with the GDNF family receptor α1 (GFRα1), which is mainly expressed by neurons and can act in cis as a membrane-bound factor or in trans as a soluble factor. The GDNF/GFRα1 complex signals through interactions with the “rearranged during transfection” (RET) receptor or via the neural cell adhesion molecule (NCAM) with a lower affinity. GDNF can also signal independently from GFRα1 by interacting with syndecan-3. RET, which is expressed by neurons involved in several pathways (nigro–striatal dopaminergic neurons, motor neurons, enteric neurons, sensory neurons, etc.), could be the main determinant of the specificity of GDNF’s pro-survival effect. In an injured brain, de novo expression of GDNF occurs in glial cells. Neuroinflammation has been reported to induce GDNF expression in activated astrocytes and microglia, infiltrating macrophages, nestin-positive reactive astrocytes, and neuron/glia (NG2) positive microglia-like cells. This disease-related GDNF overexpression can be either beneficial or detrimental depending on the localization in the brain and the level and duration of glial cell activation. Some reports also describe the upregulation of RET and GFRα1 in glial cells, suggesting that GDNF could modulate neuroinflammation.
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GDNF-mediated rescue of the nigrostriatal system depends on the degree of degeneration. Gene Ther 2018; 26:57-64. [PMID: 30531868 PMCID: PMC6514883 DOI: 10.1038/s41434-018-0049-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 10/01/2018] [Accepted: 10/12/2018] [Indexed: 02/02/2023]
Abstract
Glial cell-line derived neurotrophic factor (GDNF) is a promising therapeutic molecule to treat Parkinson’s disease. Despite an excellent profile in experimental settings, clinical trials testing GDNF have failed. One of the theories to explain these negative outcomes is that the clinical trials were done in late-stage patients that have advanced nigrostriatal degeneration and may therefore not respond to a neurotrophic factor therapy. Based on this idea, we tested if the stage of nigrostriatal degeneration is important for GDNF-based therapies. Lentiviral vectors expressing regulated GDNF were delivered to the striatum of rats to allow GDNF expression to be turned on either while the nigrostriatal system was degenerating or after the nigrostriatal system had been fully lesioned by 6-OHDA. In the group of animals where GDNF expression was on during degeneration, neurons were rescued and there was a reversal of motor deficits. Turning GDNF expression on after the nigrostriatal system was lesioned did not rescue neurons or reverse motor deficits. In fact, these animals were indistinguishable from the control groups. Our results suggest that GDNF can reverse motor deficits and nigrostriatal pathology despite an ongoing nigrostriatal degeneration, if there is still a sufficient number of remaining neurons to respond to therapy.
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