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Liu Y, Zong X, Cao W, Zhang W, Zhang N, Yang N. Gene Therapy for Retinitis Pigmentosa: Current Challenges and New Progress. Biomolecules 2024; 14:903. [PMID: 39199291 PMCID: PMC11352491 DOI: 10.3390/biom14080903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2024] [Revised: 07/14/2024] [Accepted: 07/23/2024] [Indexed: 09/01/2024] Open
Abstract
Retinitis pigmentosa (RP) poses a significant threat to eye health worldwide, with prevalence rates of 1 in 5000 worldwide. This genetically diverse retinopathy is characterized by the loss of photoreceptor cells and atrophy of the retinal pigment epithelium. Despite the involvement of more than 3000 mutations across approximately 90 genes in its onset, finding an effective treatment has been challenging for a considerable time. However, advancements in scientific research, especially in gene therapy, are significantly expanding treatment options for this most prevalent inherited eye disease, with the discovery of new compounds, gene-editing techniques, and gene loci offering hope for more effective treatments. Gene therapy, a promising technology, utilizes viral or non-viral vectors to correct genetic defects by either replacing or silencing disease-causing genes, potentially leading to complete recovery. In this review, we primarily focus on the latest applications of gene editing research in RP. We delve into the most prevalent genes associated with RP and discuss advancements in genome-editing strategies currently employed to correct various disease-causing mutations.
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Affiliation(s)
| | | | | | | | - Ningzhi Zhang
- Department of Ophthalmology, Renmin Hospital of Wuhan University, Jiefang Road #238, Wuhan 430060, China; (Y.L.); (X.Z.); (W.C.); (W.Z.)
| | - Ning Yang
- Department of Ophthalmology, Renmin Hospital of Wuhan University, Jiefang Road #238, Wuhan 430060, China; (Y.L.); (X.Z.); (W.C.); (W.Z.)
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Gariballa N, Mohamed F, Badawi S, Ali BR. The double whammy of ER-retention and dominant-negative effects in numerous autosomal dominant diseases: significance in disease mechanisms and therapy. J Biomed Sci 2024; 31:64. [PMID: 38937821 PMCID: PMC11210014 DOI: 10.1186/s12929-024-01054-1] [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: 03/24/2024] [Accepted: 06/20/2024] [Indexed: 06/29/2024] Open
Abstract
The endoplasmic reticulum (ER) employs stringent quality control mechanisms to ensure the integrity of protein folding, allowing only properly folded, processed and assembled proteins to exit the ER and reach their functional destinations. Mutant proteins unable to attain their correct tertiary conformation or form complexes with their partners are retained in the ER and subsequently degraded through ER-associated protein degradation (ERAD) and associated mechanisms. ER retention contributes to a spectrum of monogenic diseases with diverse modes of inheritance and molecular mechanisms. In autosomal dominant diseases, when mutant proteins get retained in the ER, they can interact with their wild-type counterparts. This interaction may lead to the formation of mixed dimers or aberrant complexes, disrupting their normal trafficking and function in a dominant-negative manner. The combination of ER retention and dominant-negative effects has been frequently documented to cause a significant loss of functional proteins, thereby exacerbating disease severity. This review aims to examine existing literature and provide insights into the impact of dominant-negative effects exerted by mutant proteins retained in the ER in a range of autosomal dominant diseases including skeletal and connective tissue disorders, vascular disorders, neurological disorders, eye disorders and serpinopathies. Most crucially, we aim to emphasize the importance of this area of research, offering substantial potential for understanding the factors influencing phenotypic variability associated with genetic variants. Furthermore, we highlight current and prospective therapeutic approaches targeted at ameliorating the effects of mutations exhibiting dominant-negative effects. These approaches encompass experimental studies exploring treatments and their translation into clinical practice.
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Affiliation(s)
- Nesrin Gariballa
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
| | - Feda Mohamed
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Abu Dhabi, United Arab Emirates
| | - Sally Badawi
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates
| | - Bassam R Ali
- Department of Genetics and Genomics, College of Medicine and Health Sciences, United Arab Emirates University, P.O. Box: 15551, Al-Ain, United Arab Emirates.
- ASPIRE Precision Medicine Research Institute Abu Dhabi, United Arab Emirates University, Abu Dhabi, United Arab Emirates.
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Motipally SI, Kolson DR, Guan T, Kolandaivelu S. Aberrant lipid accumulation and retinal pigmental epithelium dysfunction in PRCD-deficient mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584131. [PMID: 38558979 PMCID: PMC10979840 DOI: 10.1101/2024.03.08.584131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Progressive Rod-Cone Degeneration (PRCD) is an integral membrane protein found in photoreceptor outer segment (OS) disc membranes and its function remains unknown. Mutations in Prcd are implicated in Retinitis pigmentosa (RP) in humans and multiple dog breeds. PRCD-deficient models exhibit decreased levels of cholesterol in the plasma. However, potential changes in the retinal cholesterol remain unexplored. In addition, impaired phagocytosis observed in these animal models points to potential deficits in the retinal pigment epithelium (RPE). Here, using a Prcd -/- murine model we investigated the alterations in the retinal cholesterol levels and impairments in the structural and functional integrity of the RPE. Lipidomic and immunohistochemical analyses show a 5-fold increase in the levels of cholesteryl esters (C.Es) and accumulation of neutral lipids in the PRCD-deficient retina, respectively, indicating alterations in total retinal cholesterol. Longitudinal fundus and spectral domain optical coherence tomography (SD-OCT) examinations showed focal lesions and RPE hyperreflectivity. Strikingly, the RPE of Prcd -/- mice exhibited age-related pathological features such as neutral lipid deposits, lipofuscin accumulation, Bruch's membrane (BrM) thickening and drusenoid focal deposits, mirroring an Age-related Macular Degeneration (AMD)-like phenotype. We propose that the extensive lipofuscin accumulation likely impairs lysosomal function, leading to the defective phagocytosis observed in Prcd -/- mice. Our findings support the dysregulation of retinal cholesterol homeostasis in the absence of PRCD. Further, we demonstrate that progressive photoreceptor degeneration in Prcd -/- mice is accompanied by progressive structural and functional deficits in the RPE, which likely exacerbates vision loss over time.
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Vasudevan S, Senapati S, Pendergast M, Park PSH. Aggregation of rhodopsin mutants in mouse models of autosomal dominant retinitis pigmentosa. Nat Commun 2024; 15:1451. [PMID: 38365903 PMCID: PMC10873427 DOI: 10.1038/s41467-024-45748-4] [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: 04/07/2023] [Accepted: 02/01/2024] [Indexed: 02/18/2024] Open
Abstract
Mutations in rhodopsin can cause it to misfold and lead to retinal degeneration. A distinguishing feature of these mutants in vitro is that they mislocalize and aggregate. It is unclear whether or not these features contribute to retinal degeneration observed in vivo. The effect of P23H and G188R misfolding mutations were examined in a heterologous expression system and knockin mouse models, including a mouse model generated here expressing the G188R rhodopsin mutant. In vitro characterizations demonstrate that both mutants aggregate, with the G188R mutant exhibiting a more severe aggregation profile compared to the P23H mutant. The potential for rhodopsin mutants to aggregate in vivo was assessed by PROTEOSTAT, a dye that labels aggregated proteins. Both mutants mislocalize in photoreceptor cells and PROTEOSTAT staining was detected surrounding the nuclei of photoreceptor cells. The G188R mutant promotes a more severe retinal degeneration phenotype and greater PROTEOSTAT staining compared to that promoted by the P23H mutant. Here, we show that the level of PROTEOSTAT positive cells mirrors the progression and level of photoreceptor cell death, which suggests a potential role for rhodopsin aggregation in retinal degeneration.
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Affiliation(s)
- Sreelakshmi Vasudevan
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Subhadip Senapati
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
- Prayoga Institute of Education Research, Bengaluru, KA, 560116, India
| | - Maryanne Pendergast
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH, 44106, USA.
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Daich Varela M, Georgiadis A, Michaelides M. Genetic treatment for autosomal dominant inherited retinal dystrophies: approaches, challenges and targeted genotypes. Br J Ophthalmol 2023; 107:1223-1230. [PMID: 36038193 DOI: 10.1136/bjo-2022-321903] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Accepted: 08/01/2022] [Indexed: 11/04/2022]
Abstract
Inherited retinal diseases (IRDs) have been in the front line of gene therapy development for the last decade, providing a useful platform to test novel therapeutic approaches. More than 40 clinical trials have been completed or are ongoing, tackling autosomal recessive and X-linked conditions, mostly through adeno-associated viral vector delivery of a normal copy of the disease-causing gene. However, only recently has autosomal dominant (ad) disease been targeted, with the commencement of a trial for rhodopsin (RHO)-associated retinitis pigmentosa (RP), implementing antisense oligonucleotide (AON) therapy, with promising preliminary results (NCT04123626).Autosomal dominant RP represents 15%-25% of all RP, with RHO accounting for 20%-30% of these cases. Autosomal dominant macular and cone-rod dystrophies (MD/CORD) correspond to approximately 7.5% of all IRDs, and approximately 35% of all MD/CORD cases, with the main causative gene being BEST1 Autosomal dominant IRDs are not only less frequent than recessive, but also tend to be less severe and have later onset; for example, an individual with RHO-adRP would typically become severely visually impaired at an age 2-3 times older than in X-linked RPGR-RP.Gain-of-function and dominant negative aetiologies are frequently seen in the prevalent adRP genes RHO, RP1 and PRPF31 among others, which would not be effectively addressed by gene supplementation alone and need creative, novel approaches. Zinc fingers, RNA interference, AON, translational read-through therapy, and gene editing by clustered regularly interspaced short palindromic repeats/Cas are some of the strategies that are currently under investigation and will be discussed here.
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Affiliation(s)
- Malena Daich Varela
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
| | | | - Michel Michaelides
- Moorfields Eye Hospital, London, UK
- UCL Institute of Ophthalmology, University College London, London, UK
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Sp S, Mitra RN, Zheng M, Chrispell JD, Wang K, Kwon YS, Weiss ER, Han Z. Gene augmentation for autosomal dominant retinitis pigmentosa using rhodopsin genomic loci nanoparticles in the P23H +/- knock-in murine model. Gene Ther 2023; 30:628-640. [PMID: 36935427 DOI: 10.1038/s41434-023-00394-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Revised: 02/13/2023] [Accepted: 02/28/2023] [Indexed: 03/21/2023]
Abstract
Gene therapy for autosomal dominant retinitis pigmentosa (adRP) is challenged by the dominant inheritance of the mutant genes, which would seemingly require a combination of mutant suppression and wild-type replacement of the appropriate gene. We explore the possibility that delivery of a nanoparticle (NP)-mediated full-length mouse genomic rhodopsin (gRho) or human genomic rhodopsin (gRHO) locus can overcome the dominant negative effects of the mutant rhodopsin in the clinically relevant P23H+/--knock-in heterozygous mouse model. Our results demonstrate that mice in both gRho and gRHO NP-treated groups exhibit significant structural and functional recovery of the rod photoreceptors, which lasted for 3 months post-injection, indicating a promising reduction in photoreceptor degeneration. We performed miRNA transcriptome analysis using next generation sequencing and detected differentially expressed miRNAs as a first step towards identifying miRNAs that could potentially be used as rhodopsin gene expression enhancers or suppressors for sustained photoreceptor rescue. Our results indicate that delivering an intact genomic locus as a transgene has a greater chance of success compared to the use of the cDNA for treatment of this model of adRP, emphasizing the importance of gene augmentation using a gDNA that includes regulatory elements.
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Affiliation(s)
- Simna Sp
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Rajendra N Mitra
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Min Zheng
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Jared D Chrispell
- Department of Cell Biology and Physiology, the University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Kai Wang
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Yong-Su Kwon
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Ellen R Weiss
- Department of Cell Biology and Physiology, the University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Zongchao Han
- Department of Ophthalmology, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Carolina Institute for NanoMedicine, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
- Division of Pharmacoengineering & Molecular Pharmaceutics, Eshelman School of Pharmacy, the University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599, USA.
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Lewis TR, Phan S, Castillo CM, Kim KY, Coppenrath K, Thomas W, Hao Y, Skiba NP, Horb ME, Ellisman MH, Arshavsky VY. Photoreceptor disc incisures form as an adaptive mechanism ensuring the completion of disc enclosure. eLife 2023; 12:e89160. [PMID: 37449984 PMCID: PMC10361718 DOI: 10.7554/elife.89160] [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: 05/05/2023] [Accepted: 07/13/2023] [Indexed: 07/18/2023] Open
Abstract
The first steps of vision take place within a stack of tightly packed disc-shaped membranes, or 'discs', located in the outer segment compartment of photoreceptor cells. In rod photoreceptors, discs are enclosed inside the outer segment and contain deep indentations in their rims called 'incisures'. The presence of incisures has been documented in a variety of species, yet their role remains elusive. In this study, we combined traditional electron microscopy with three-dimensional electron tomography to demonstrate that incisures are formed only after discs become completely enclosed. We also observed that, at the earliest stage of their formation, discs are not round as typically depicted but rather are highly irregular in shape and resemble expanding lamellipodia. Using genetically manipulated mice and frogs and measuring outer segment protein abundances by quantitative mass spectrometry, we further found that incisure size is determined by the molar ratio between peripherin-2, a disc rim protein critical for the process of disc enclosure, and rhodopsin, the major structural component of disc membranes. While a high perpherin-2 to rhodopsin ratio causes an increase in incisure size and structural complexity, a low ratio precludes incisure formation. Based on these data, we propose a model whereby normal rods express a modest excess of peripherin-2 over the amount required for complete disc enclosure in order to ensure that this important step of disc formation is accomplished. Once the disc is enclosed, the excess peripherin-2 incorporates into the rim to form an incisure.
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Affiliation(s)
- Tylor R Lewis
- Department of Ophthalmology, Duke University Medical CenterDurhamUnited States
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San DiegoLa JollaUnited States
| | - Carson M Castillo
- Department of Ophthalmology, Duke University Medical CenterDurhamUnited States
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San DiegoLa JollaUnited States
| | - Kelsey Coppenrath
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus ResourceWoods HoleUnited States
| | - William Thomas
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus ResourceWoods HoleUnited States
| | - Ying Hao
- Department of Ophthalmology, Duke University Medical CenterDurhamUnited States
| | - Nikolai P Skiba
- Department of Ophthalmology, Duke University Medical CenterDurhamUnited States
| | - Marko E Horb
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus ResourceWoods HoleUnited States
| | - Mark H Ellisman
- National Center for Microscopy and Imaging Research, School of Medicine, University of California, San DiegoLa JollaUnited States
| | - Vadim Y Arshavsky
- Department of Ophthalmology, Duke University Medical CenterDurhamUnited States
- Department of Pharmacology and Cancer Biology, Duke University Medical CenterDurhamUnited States
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Justin GA, Girach A, Maldonado RS. Antisense oligonucleotide therapy for proline-23-histidine autosomal dominant retinitis pigmentosa. Curr Opin Ophthalmol 2023; 34:226-231. [PMID: 36924362 DOI: 10.1097/icu.0000000000000947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/18/2023]
Abstract
PURPOSE OF REVIEW To discuss antisense oligonucleotide (ASON) therapy for autosomal dominant retinitis pigmentosa (adRP) caused by the proline-23-histidine (P23H) mutation in the rhodopsin gene. RECENT FINDINGS Viral and nonviral therapies to treat adRP are currently under investigation. A promising therapeutic option is a nonviral approach using ASONs. This form of genetic therapy has demonstrated a dose-dependent and highly selective reduction of P23H mutant rhodopsin mRNA in animal models, and it is currently being investigated as a human phase 1/2 clinical trial. SUMMARY There are promising new therapies to treat adRP. ASON has shown encouraging results in animal models and has undergone a phase 1 clinical trial. ASON does not use a viral vector, is delivered with standard intravitreal injection, and its effects are reversible.
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Affiliation(s)
- Grant A Justin
- Department of Ophthalmology, Duke University, Durham, North Carolina, USA
| | | | - Ramiro S Maldonado
- Department of Ophthalmology, Duke University, Durham, North Carolina, USA
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Lewis TR, Phan S, Castillo CM, Kim KY, Coppenrath K, Thomas W, Hao Y, Skiba NP, Horb ME, Ellisman MH, Arshavsky VY. Photoreceptor disc incisures form as an adaptive mechanism ensuring the completion of disc enclosure. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.06.535932. [PMID: 37066355 PMCID: PMC10104153 DOI: 10.1101/2023.04.06.535932] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/18/2023]
Abstract
The first steps of vision take place within a stack of tightly packed disc-shaped membranes, or "discs", located in the outer segment compartment of photoreceptor cells. In rod photoreceptors, discs are enclosed inside the outer segment and contain deep indentations in their rims called "incisures". The presence of incisures has been documented in a variety of species, yet their role remains elusive. In this study, we combined traditional electron microscopy with three-dimensional electron tomography to demonstrate that incisures are formed only after discs become completely enclosed. We also observed that, at the earliest stage of their formation, discs are not round as typically depicted but rather are highly irregular in shape and resemble expanding lamellipodia. Using genetically manipulated mice and frogs and measuring outer segment protein abundances by quantitative mass spectrometry, we further found that incisure size is determined by the molar ratio between peripherin-2, a disc rim protein critical for the process of disc enclosure, and rhodopsin, the major structural component of disc membranes. While a high perpherin-2 to rhodopsin ratio causes an increase in incisure size and structural complexity, a low ratio precludes incisure formation. Based on these data, we propose a model whereby normal rods express a modest excess of peripherin-2 over the amount required for complete disc enclosure in order to ensure that this important step of disc formation is accomplished. Once the disc is enclosed, the excess peripherin-2 incorporates into the rim to form an incisure.
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Affiliation(s)
- Tylor R. Lewis
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA, 27710
| | - Sebastien Phan
- National Center for Microscopy and Imaging Research, School of Medicine, University of California San Diego, La Jolla, CA, USA, 92093
| | - Carson M. Castillo
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA, 27710
| | - Keun-Young Kim
- National Center for Microscopy and Imaging Research, School of Medicine, University of California San Diego, La Jolla, CA, USA, 92093
| | - Kelsey Coppenrath
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Woods Hole, MA, USA, 02543
| | - William Thomas
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Woods Hole, MA, USA, 02543
| | - Ying Hao
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA, 27710
| | - Nikolai P. Skiba
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA, 27710
| | - Marko E. Horb
- Eugene Bell Center for Regenerative Biology and Tissue Engineering and National Xenopus Resource, Woods Hole, MA, USA, 02543
| | - Mark H. Ellisman
- National Center for Microscopy and Imaging Research, School of Medicine, University of California San Diego, La Jolla, CA, USA, 92093
| | - Vadim Y. Arshavsky
- Department of Ophthalmology, Duke University Medical Center, Durham, NC, USA, 27710
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, NC, USA, 27710
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Langouët M, Jolicoeur C, Javed A, Mattar P, Gearhart MD, Daiger SP, Bertelsen M, Tranebjærg L, Rendtorff ND, Grønskov K, Jespersgaard C, Chen R, Sun Z, Li H, Alirezaie N, Majewski J, Bardwell VJ, Sui R, Koenekoop RK, Cayouette M. Mutations in BCOR, a co-repressor of CRX/OTX2, are associated with early-onset retinal degeneration. SCIENCE ADVANCES 2022; 8:eabh2868. [PMID: 36070393 PMCID: PMC9451151 DOI: 10.1126/sciadv.abh2868] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2021] [Accepted: 07/21/2022] [Indexed: 06/10/2023]
Abstract
Many transcription factors regulating the production, survival, and function of photoreceptor cells have been identified, but little is known about transcriptional co-regulators in retinal health and disease. Here, we show that BCL6 co-repressor (BCOR), a Polycomb repressive complex 1 factor mutated in various cancers, is involved in photoreceptor degenerative diseases. Using proteomics and transcription assays, we report that BCOR interacts with the transcription factors CRX and OTX2 and reduces their ability to activate the promoters of photoreceptor-specific genes. CUT&RUN sequencing further shows that BCOR shares genome-wide binding profiles with CRX/OTX2, consistent with a general co-repression activity. We also identify missense mutations in human BCOR in five families that have no evidence of cancer but present severe early-onset X-linked retinal degeneration. Last, we show that the human BCOR mutants cause degeneration when expressed in the mouse retina and have enhanced repressive activity on OTX2. These results uncover a role for BCOR in photoreceptors in both health and disease.
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Affiliation(s)
- Maéva Langouët
- Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Christine Jolicoeur
- Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Awais Javed
- Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Pierre Mattar
- Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
| | - Micah D. Gearhart
- Department of Genetics, Cell Biology and Development, Development Biology Center, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Stephen P. Daiger
- EHGED Department, Human Genetics Center, School of Public Health, University of Texas HSC, Houston, TX 77030, USA
| | - Mette Bertelsen
- Department of Clinical Genetics, Rigshospitalet, The Kennedy Centre, Copenhagen, Denmark
- Department of Ophthalmology, Rigshospitalet, The Kennedy Centre, Glostrup, Denmark
| | - Lisbeth Tranebjærg
- Department of Clinical Genetics, Rigshospitalet, The Kennedy Centre, Copenhagen, Denmark
- Institute of Clinical Medicine, University of Copenhagen, Denmark
| | - Nanna D. Rendtorff
- Department of Clinical Genetics, Rigshospitalet, The Kennedy Centre, Copenhagen, Denmark
| | - Karen Grønskov
- Department of Clinical Genetics, Rigshospitalet, The Kennedy Centre, Copenhagen, Denmark
| | - Catherine Jespersgaard
- Department of Clinical Genetics, Rigshospitalet, The Kennedy Centre, Copenhagen, Denmark
| | - Rui Chen
- Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Zixi Sun
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
| | - Hui Li
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
| | - Najmeh Alirezaie
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Jacek Majewski
- Department of Human Genetics, McGill University, Montreal, QC, Canada
| | - Vivian J. Bardwell
- Department of Genetics, Cell Biology and Development, Development Biology Center, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ruifang Sui
- Department of Ophthalmology, State Key Laboratory of Complex Severe and Rare diseases, Peking Union Medical College Hospital, Chinese Academy of Medical Science and Peking Union Medical College, Beijing 100730, China
| | - Robert K. Koenekoop
- Departments of Pediatric Surgery, Human Genetics, Adult Ophthalmology and the McGill Ocular Genetics Laboratory, McGill University Health Center Research Institute, Montreal, QC, Canada
| | - Michel Cayouette
- Cellular Neurobiology Research Unit, Institut de Recherches Cliniques de Montréal (IRCM), Montréal, QC H2W 1R7, Canada
- Department of Medicine, Université de Montréal, Montreal, QC, Canada
- Department of Anatomy and Cell Biology, Division of Experimental Medicine, McGill University, Montreal, QC, Canada
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11
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Ziółkowska N, Lewczuk B. Profiles of Rho, Opn4, c-Fos, and Birc5 mRNA expression in Wistar rat retinas exposed to white or monochromatic light. Front Neuroanat 2022; 16:956000. [PMID: 36059433 PMCID: PMC9434339 DOI: 10.3389/fnana.2022.956000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2022] [Accepted: 07/21/2022] [Indexed: 11/30/2022] Open
Abstract
Despite concern over potential retinal damage linked to exposure to light-emitting-diode (LED) light (particularly blue light), it remains unknown how exposure to low-intensity monochromatic LED light affects the expression of rhodopsin (Rho, a photopigment that mediates light-induced retinal degeneration), melanopsin (Opn4, a blue-light sensitive photopigment), c-Fos (associated with retinal damage/degeneration), and Birc5 (anti-apoptotic). This study investigated the mRNA expression profiles of these genes under exposure to white and monochromatic light (blue, red, green) in the retinas of albino rats under a cycle of 12 h of light and 12 h of darkness. In each group, 32 Wistar rats were exposed to one type of monochromatic-LED or white-fluorescent light for 7 day (150 lx). Retinal samples were taken for qPCR analysis and light and electron microscopy. Blue and green light exposure markedly decreased expression of Rho and Opn4 mRNA and increased expression of Birc5 and c-Fos mRNA (P < 0.05). In retinas from the blue-light group, loss and vesiculation of photoreceptor outer segments were visible, but not in retinas from the red-light and control group. Measurements of the photoreceptor inner and outer segments length revealed, that this length was significantly decreased in the blue- and green-light exposure groups (P < 0.02), but not in the red-light exposure group. Increased expression of Birc5 and decreased expression of Rho and Opn4 after exposure to blue and green light may be early responses that help to reduce light-induced retinal damage.
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Affiliation(s)
- Natalia Ziółkowska
- Department of Histology and Embryology, Faculty of Veterinary Medicine, University of Warmia and Mazury in Olsztyn, Olsztyn, Poland
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12
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Massengill MT, Lewin AS. Gene Therapy for Rhodopsin-associated Autosomal Dominant Retinitis Pigmentosa. Int Ophthalmol Clin 2021; 61:79-96. [PMID: 34584046 PMCID: PMC8478325 DOI: 10.1097/iio.0000000000000383] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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13
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Xiao YS, Liang J, Gao M, Sun JR, Liu Y, Chen JQ, Zhao XH, Wang YM, Chen YH, Wang YW, Wan XL, Luo XT, Sun XD. Deletion of prominin-1 in mice results in disrupted photoreceptor outer segment protein homeostasis. Int J Ophthalmol 2021; 14:1334-1344. [PMID: 34540608 PMCID: PMC8403851 DOI: 10.18240/ijo.2021.09.07] [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: 01/28/2021] [Accepted: 04/21/2021] [Indexed: 11/23/2022] Open
Abstract
AIM To illustrate the underlying mechanism how prominin-1 (also known as Prom1) mutation contribute to progressive photoreceptor degeneration. METHODS A CRISPR-mediated Prom1 knockout (Prom1-KO) mice model in the C57BL/6 was generated and the photoreceptor degeneration phenotypes by means of structural and functional tests were demonstrated. Immunohistochemistry and immunoblot analysis were performed to reveal the localization and quantity of related outer segment (OS) proteins. RESULTS The Prom1-KO mice developed the photoreceptor degeneration phenotype including the decreased outer nuclear layer (ONL) thickness and compromised electroretinogram amplitude. Immunohistochemistry analysis revealed impaired trafficking of photoreceptor OS proteins. Immunoblot data demonstrated decreased photoreceptor OS proteins. CONCLUSION Prom1 deprivation causes progressive photoreceptor degeneration. Prom1 is essential for maintaining normal trafficking and normal quantity of photoreceptor OS proteins. The new light is shed on the pathogenic mechanism underlying photoreceptor degeneration caused by Prom1 mutation.
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Affiliation(s)
- Yu-Shu Xiao
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Jian Liang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Fundus Diseases, Shanghai 200080, China
| | - Min Gao
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Jun-Ran Sun
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Yang Liu
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Jie-Qiong Chen
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Xiao-Huan Zhao
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Yi-Min Wang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Yu-Hong Chen
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Yu-Wei Wang
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
| | - Xiao-Ling Wan
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Fundus Diseases, Shanghai 200080, China
| | - Xue-Ting Luo
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Fundus Diseases, Shanghai 200080, China
| | - Xiao-Dong Sun
- Department of Ophthalmology, Shanghai General Hospital (Shanghai First People's Hospital), Shanghai Jiao Tong University, School of Medicine, Shanghai 200080, China
- Shanghai Key Laboratory of Fundus Diseases, Shanghai 200080, China
- Shanghai Engineering Center for Visual Science and Photomedicine, Shanghai 200080, China
- National Clinical Research Center for Ophthalmic Diseases, Shanghai 200080, China
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Mirtron-mediated RNA knockdown/replacement therapy for the treatment of dominant retinitis pigmentosa. Nat Commun 2021; 12:4934. [PMID: 34400638 PMCID: PMC8368061 DOI: 10.1038/s41467-021-25204-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 07/26/2021] [Indexed: 02/07/2023] Open
Abstract
Rhodopsin (RHO) gene mutations are a common cause of autosomal dominant retinitis pigmentosa (ADRP). The need to suppress toxic protein expression together with mutational heterogeneity pose challenges for treatment development. Mirtrons are atypical RNA interference effectors that are spliced from transcripts as short introns. Here, we develop a novel mirtron-based knockdown/replacement gene therapy for the mutation-independent treatment of RHO-related ADRP, and demonstrate efficacy in a relevant mammalian model. Splicing and potency of rhodopsin-targeting candidate mirtrons are initially determined, and a mirtron-resistant codon-modified version of the rhodopsin coding sequence is validated in vitro. These elements are then combined within a single adeno-associated virus (AAV) and delivered subretinally in a RhoP23H knock-in mouse model of ADRP. This results in significant mouse-to-human rhodopsin RNA replacement and is associated with a slowing of retinal degeneration. This provides proof of principle that synthetic mirtrons delivered by AAV are capable of reducing disease severity in vivo.
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15
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Colozo AT, Vasudevan S, Park PSH. Retinal degeneration in mice expressing the constitutively active G90D rhodopsin mutant. Hum Mol Genet 2021; 29:881-891. [PMID: 31960909 DOI: 10.1093/hmg/ddaa008] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/11/2019] [Accepted: 01/15/2020] [Indexed: 11/13/2022] Open
Abstract
Rhodopsin is the G protein-coupled receptor in rod photoreceptor cells that initiates vision upon photon capture. The light receptor is normally locked in an inactive state in the dark by the covalently bound inverse agonist 11-cis retinal. Mutations can render the receptor active even in the absence of light. This constitutive activity can desensitize rod photoreceptor cells and lead to night blindness. A G90D mutation in rhodopsin causes the receptor to be constitutively active and leads to congenital stationary night blindness, which is generally thought to be devoid of retinal degeneration. The constitutively active species responsible for the night blindness phenotype is unclear. Moreover, the classification as a stationary disease devoid of retinal degeneration is also misleading. A transgenic mouse model for congenital stationary night blindness that expresses the G90D rhodopsin mutant was examined to better understand the origin of constitutive activity and the potential for retinal degeneration. Heterozygous mice for the G90D mutation did not exhibit retinal degeneration whereas homozygous mice exhibited progressive retinal degeneration. Only a modest reversal of retinal degeneration was observed when transducin signaling was eliminated genetically, indicating that some of the retinal degeneration occurred in a transducin-independent manner. Biochemical studies on purified rhodopsin from mice indicated that multiple species can potentially contribute to the constitutive activity causing night blindness.
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Affiliation(s)
- Alejandro T Colozo
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Sreelakshmi Vasudevan
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
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16
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Patrizi C, Llado M, Benati D, Iodice C, Marrocco E, Guarascio R, Surace EM, Cheetham ME, Auricchio A, Recchia A. Allele-specific editing ameliorates dominant retinitis pigmentosa in a transgenic mouse model. Am J Hum Genet 2021; 108:295-308. [PMID: 33508235 PMCID: PMC7896132 DOI: 10.1016/j.ajhg.2021.01.006] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 01/08/2021] [Indexed: 12/11/2022] Open
Abstract
Retinitis pigmentosa (RP) is a group of progressive retinal degenerations of mostly monogenic inheritance, which cause blindness in about 1:3,500 individuals worldwide. Heterozygous variants in the rhodopsin (RHO) gene are the most common cause of autosomal dominant RP (adRP). Among these, missense variants at C-terminal proline 347, such as p.Pro347Ser, cause severe adRP recurrently in European affected individuals. Here, for the first time, we use CRISPR/Cas9 to selectively target the p.Pro347Ser variant while preserving the wild-type RHO allele in vitro and in a mouse model of adRP. Detailed in vitro, genomic, and biochemical characterization of the rhodopsin C-terminal editing demonstrates a safe downregulation of p.Pro347Ser expression leading to partial recovery of photoreceptor function in a transgenic mouse model treated with adeno-associated viral vectors. This study supports the safety and efficacy of CRISPR/Cas9-mediated allele-specific editing and paves the way for a permanent and precise correction of heterozygous variants in dominantly inherited retinal diseases.
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Affiliation(s)
- Clarissa Patrizi
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Manel Llado
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Daniela Benati
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy
| | - Carolina Iodice
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | - Elena Marrocco
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy
| | | | - Enrico M Surace
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy; Medical Genetics, Department of Translational Medicine, Federico II University, 80125 Naples, Italy
| | | | - Alberto Auricchio
- Telethon Institute of Genetics and Medicine, 80078 Pozzuoli, Italy; Medical Genetics, Department of Advanced Biomedicine, Federico II University, 80125 Naples, Italy.
| | - Alessandra Recchia
- Centre for Regenerative Medicine, Department of Life Sciences, University of Modena and Reggio Emilia, 41125 Modena, Italy.
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17
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Das Y, Swinkels D, Kocherlakota S, Vinckier S, Vaz FM, Wever E, van Kampen AHC, Jun B, Do KV, Moons L, Bazan NG, Van Veldhoven PP, Baes M. Peroxisomal Multifunctional Protein 2 Deficiency Perturbs Lipid Homeostasis in the Retina and Causes Visual Dysfunction in Mice. Front Cell Dev Biol 2021; 9:632930. [PMID: 33604342 PMCID: PMC7884615 DOI: 10.3389/fcell.2021.632930] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 01/11/2021] [Indexed: 01/09/2023] Open
Abstract
Patients lacking multifunctional protein 2 (MFP2), the central enzyme of the peroxisomal β-oxidation pathway, develop retinopathy. This pathway is involved in the metabolism of very long chain (VLCFAs) and polyunsaturated (PUFAs) fatty acids, which are enriched in the photoreceptor outer segments (POS). The molecular mechanisms underlying the retinopathy remain, however, elusive. Here, we report that mice with MFP2 inactivation display decreased retinal function already at the age of 3 weeks, which is accompanied by a profound shortening of the photoreceptor outer and inner segments, but with preserved photoreceptor ultrastructure. Furthermore, MFP2 deficient retinas exhibit severe changes in gene expression with downregulation of genes involved in the phototransduction pathway and upregulation of inflammation related genes. Lipid profiling of the mutant retinas revealed a profound reduction of DHA-containing phospholipids. This was likely due to a hampered systemic supply and retinal traffic of this PUFA, although we cannot exclude that the local defect of peroxisomal β-oxidation contributes to this DHA decrease. Moreover, very long chain PUFAs were also reduced, with the exception of those containing ≥ 34 carbons that accumulated. The latter suggests that there is an uncontrollable elongation of retinal PUFAs. In conclusion, our data reveal that intact peroxisomal β-oxidation is indispensable for retinal integrity, most likely by maintaining PUFA homeostasis.
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Affiliation(s)
- Yannick Das
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Daniëlle Swinkels
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Sai Kocherlakota
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
| | - Stefan Vinckier
- Laboratory of Angiogenesis and Vascular Metabolism, Department of Oncology, KU Leuven-VIB, Leuven, Belgium
| | - Frédéric M Vaz
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Core Facility Metabolomics, Amsterdam University Medical Center (UMC), Amsterdam, Netherlands
| | - Eric Wever
- Laboratory of Genetic Metabolic Diseases, Department of Clinical Chemistry and Pediatrics, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Core Facility Metabolomics, Amsterdam University Medical Center (UMC), Amsterdam, Netherlands.,Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands
| | - Antoine H C van Kampen
- Bioinformatics Laboratory, Department of Epidemiology and Data Science, Amsterdam Public Health Research Institute, Amsterdam University Medical Center (UMC), University of Amsterdam, Amsterdam, Netherlands.,Biosystems Data Analysis, Swammerdam Institute for Life Sciences, University of Amsterdam, Amsterdam, Netherlands
| | - Bokkyoo Jun
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Khanh V Do
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Lieve Moons
- Animal Physiology and Neurobiology, Department of Biology, KU Leuven, Leuven, Belgium
| | - Nicolas G Bazan
- Neuroscience Center of Excellence, School of Medicine, Louisiana State University Health New Orleans, New Orleans, LA, United States
| | - Paul P Van Veldhoven
- Lipid Biochemistry and Protein Interactions (LIPIT), Department of Cellular and Molecular Medicine, KU Leuven, Leuven, Belgium
| | - Myriam Baes
- Laboratory of Cell Metabolism, Department of Pharmaceutical and Pharmacological Sciences, KU Leuven, Leuven, Belgium
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18
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Hebbar S, Lehmann M, Behrens S, Hälsig C, Leng W, Yuan M, Winkler S, Knust E. Mutations in the splicing regulator Prp31 lead to retinal degeneration in Drosophila. Biol Open 2021; 10:10/1/bio052332. [PMID: 33495354 PMCID: PMC7860132 DOI: 10.1242/bio.052332] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Retinitis pigmentosa (RP) is a clinically heterogeneous disease affecting 1.6 million people worldwide. The second-largest group of genes causing autosomal dominant RP in human encodes regulators of the splicing machinery. Yet, how defects in splicing factor genes are linked to the aetiology of the disease remains largely elusive. To explore possible mechanisms underlying retinal degeneration caused by mutations in regulators of the splicing machinery, we induced mutations in Drosophila Prp31, the orthologue of human PRPF31, mutations in which are associated with RP11. Flies heterozygous mutant for Prp31 are viable and develop normal eyes and retina. However, photoreceptors degenerate under light stress, thus resembling the human disease phenotype. Degeneration is associated with increased accumulation of the visual pigment rhodopsin 1 and increased mRNA levels of twinfilin, a gene associated with rhodopsin trafficking. Reducing rhodopsin levels by raising animals in a carotenoid-free medium not only attenuates rhodopsin accumulation, but also retinal degeneration. Given a similar importance of proper rhodopsin trafficking for photoreceptor homeostasis in human, results obtained in flies presented here will also contribute to further unravel molecular mechanisms underlying the human disease. This paper has an associated First Person interview with the co-first authors of the article. Summary: Retinitis pigmentosa (RP) is a human disease resulting in blindness, which affects 1 in 4.000 people worldwide. So far >90 genes have been identified that are causally related to RP. Mutations in the splicing factor PRPF31 are linked to RP11. We induced mutations in the Drosophila orthologue Prp31 and show that flies heterozygous for Prp31 undergo light-dependent retinal degeneration. Degeneration is associated with increased accumulation of the light-sensitive molecule, rhodopsin 1. In fact, reducing rhodopsin levels by dietary intervention modifies the extent of retinal degeneration. This model will further contribute to better understand the aetiology of the human disease.
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Affiliation(s)
- Sarita Hebbar
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Malte Lehmann
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Sarah Behrens
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Catrin Hälsig
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Weihua Leng
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Michaela Yuan
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Sylke Winkler
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
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Kantor A, McClements ME, Peddle CF, Fry LE, Salman A, Cehajic-Kapetanovic J, Xue K, MacLaren RE. CRISPR genome engineering for retinal diseases. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 182:29-79. [PMID: 34175046 DOI: 10.1016/bs.pmbts.2021.01.024] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Novel gene therapy treatments for inherited retinal diseases have been at the forefront of translational medicine over the past couple of decades. Since the discovery of CRISPR mechanisms and their potential application for the treatment of inherited human conditions, it seemed inevitable that advances would soon be made using retinal models of disease. The development of CRISPR technology for gene therapy and its increasing potential to selectively target disease-causing nucleotide changes has been rapid. In this chapter, we discuss the currently available CRISPR toolkit and how it has been and can be applied in the future for the treatment of inherited retinal diseases. These blinding conditions have until now had limited opportunity for successful therapeutic intervention, but the discovery of CRISPR has created new hope of achieving such, as we discuss within this chapter.
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Affiliation(s)
- Ariel Kantor
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom.
| | - Michelle E McClements
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Caroline F Peddle
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Lewis E Fry
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Ahmed Salman
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom
| | - Jasmina Cehajic-Kapetanovic
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Kanmin Xue
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
| | - Robert E MacLaren
- Nuffield Laboratory of Ophthalmology, Nuffield Department of Clinical Neurosciences & NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, United Kingdom; Oxford Eye Hospital, Oxford University Hospitals NHS Foundation Trust, Oxford, United Kingdom
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20
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Meschede IP, Burgoyne T, Tolmachova T, Seabra MC, Futter CE. Chronically shortened rod outer segments accompany photoreceptor cell death in Choroideremia. PLoS One 2020; 15:e0242284. [PMID: 33201897 PMCID: PMC7671558 DOI: 10.1371/journal.pone.0242284] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 10/29/2020] [Indexed: 01/28/2023] Open
Abstract
X-linked choroideremia (CHM) is a disease characterized by gradual retinal degeneration caused by loss of the Rab Escort Protein, REP1. Despite partial compensation by REP2 the disease is characterized by prenylation defects in multiple members of the Rab protein family that are master regulators of membrane traffic. Remarkably, the eye is the only organ affected in CHM patients, possibly because of the huge membrane traffic burden of the post mitotic photoreceptors, which synthesise outer segments, and the adjacent retinal pigment epithelium that degrades the spent portions each day. In this study, we aimed to identify defects in membrane traffic that might lead to photoreceptor cell death in CHM. In a heterozygous null female mouse model of CHM (Chmnull/WT), degeneration of the photoreceptor layer was clearly evident from increased numbers of TUNEL positive cells compared to age matched controls, small numbers of cells exhibiting signs of mitochondrial stress and greatly increased microglial infiltration. However, most rod photoreceptors exhibited remarkably normal morphology with well-formed outer segments and no discernible accumulation of transport vesicles in the inner segment. The major evidence of membrane trafficking defects was a shortening of rod outer segments that was evident at 2 months of age but remained constant over the period during which the cells die. A decrease in rhodopsin density found in the outer segment may underlie the outer segment shortening but does not lead to rhodopsin accumulation in the inner segment. Our data argue against defects in rhodopsin transport or outer segment renewal as triggers of cell death in CHM.
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Affiliation(s)
| | | | | | - Miguel C. Seabra
- UCL Institute of Ophthalmology, London, United Kingdom
- Imperial College London, London, United Kingdom
- CEDOC, NOVA Universidade Nova de Lisboa, Lisbon, Portugal
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21
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Nadolski NJ, Balay SD, Wong CXL, Waskiewicz AJ, Hocking JC. Abnormal Cone and Rod Photoreceptor Morphogenesis in gdf6a Mutant Zebrafish. Invest Ophthalmol Vis Sci 2020; 61:9. [PMID: 32293666 PMCID: PMC7401959 DOI: 10.1167/iovs.61.4.9] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Analysis of photoreceptor morphology and gene expression in mispatterned eyes of zebrafish growth differentiation factor 6a (gdf6a) mutants. Methods Rod and cone photoreceptors were compared between gdf6a mutant and control zebrafish from larval to late adult stages using transgenic labels, immunofluorescence, and confocal microscopy, as well as by transmission electron microscopy. To compare transcriptomes between larval gdf6a mutant and control zebrafish, RNA-Seq was performed on isolated eyes. Results Although rod and cone photoreceptors differentiate in gdf6a mutant zebrafish, the cells display aberrant growth and morphology. The cone outer segments, the light-detecting sensory endings, are reduced in size in the mutant larvae and fail to recover to control size at subsequent stages. In contrast, rods form temporarily expanded outer segments. The inner segments, which generate the required energy and proteins for the outer segments, are shortened in both rods and cones at all stages. RNA-Seq analysis provides a set of misregulated genes associated with the observed abnormal photoreceptor morphogenesis. Conclusions GDF6 mutations were previously identified in patients with Leber congenital amaurosis. Here, we reveal a unique photoreceptor phenotype in the gdf6a mutant zebrafish whereby rods and cones undergo abnormal maturation distinct for each cell type. Further, subsequent development shows partial recovery of cell morphology and maintenance of the photoreceptor layer. By conducting a transcriptomic analysis of the gdf6a larval eyes, we identified a collection of genes that are candidate regulators of photoreceptor size and morphology.
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22
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Orlans HO, Barnard AR, Patrício MI, McClements ME, MacLaren RE. Effect of AAV-Mediated Rhodopsin Gene Augmentation on Retinal Degeneration Caused by the Dominant P23H Rhodopsin Mutation in a Knock-In Murine Model. Hum Gene Ther 2020; 31:730-742. [DOI: 10.1089/hum.2020.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Affiliation(s)
- Harry O. Orlans
- Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford, United Kingdom
- Moorfields Eye Hospital, London, United Kingdom
| | - Alun R. Barnard
- Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford, United Kingdom
| | - Maria I. Patrício
- Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford, United Kingdom
| | | | - Robert E. MacLaren
- Nuffield Laboratory of Ophthalmology, John Radcliffe Hospital, Oxford, United Kingdom
- Moorfields Eye Hospital, London, United Kingdom
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23
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Scott BM, Wybenga-Groot LE, McGlade CJ, Heon E, Peisajovich SG, Chang BSW. Screening of Chemical Libraries Using a Yeast Model of Retinal Disease. SLAS DISCOVERY 2019; 24:969-977. [PMID: 31556794 DOI: 10.1177/2472555219875934] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Retinitis pigmentosa (RP) is a degenerative retinal disease, often caused by mutations in the G-protein-coupled receptor rhodopsin. The majority of pathogenic rhodopsin mutations cause rhodopsin to misfold, including P23H, disrupting its crucial ability to respond to light. Previous screens to discover pharmacological chaperones of rhodopsin have primarily been based on rescuing rhodopsin trafficking and localization to the plasma membrane. Here, we present methods utilizing a yeast-based assay to screen for compounds that rescue the ability of rhodopsin to activate an associated downstream G-protein signaling cascade. We engineered a yeast strain in which human rhodopsin variants were genomically integrated, and were able to demonstrate functional coupling to the yeast mating pathway, leading to fluorescent protein expression. We confirmed that a known pharmacological chaperone, 9-cis retinal, could partially rescue light-dependent activation of a disease-associated rhodopsin mutation (P23H) expressed in yeast. These novel yeast strains were used to perform a phenotypic screen of 4280 compounds from the LOPAC1280 library and a peptidomimetic library, to discover novel pharmacological chaperones of rhodopsin. The fluorescence-based assay was robust in a 96-well format, with a Z' factor of 0.65 and a signal-to-background ratio of above 14. One compound was selected for additional analysis, but it did not appear to rescue rhodopsin function in yeast. The methods presented here are amenable to future screens of small-molecule libraries, as they are robust and cost-effective. We also discuss how these methods could be further modified or adapted to perform screens of more compounds in the future.
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Affiliation(s)
- Benjamin M Scott
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.,Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.,Biosystems and Biomaterials Division, National Institute of Standards and Technology, Gaithersburg, MD, USA
| | | | - C Jane McGlade
- Department of Medical Biophysics, University of Toronto, Toronto, ON, Canada.,Program in Cell Biology, The Hospital for Sick Children, Toronto, ON, Canada
| | - Elise Heon
- Department of Ophthalmology and Vision Science, The Hospital for Sick Children, Toronto, ON, Canada
| | - Sergio G Peisajovich
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Belinda S W Chang
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada.,Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, ON, Canada.,Centre for the Analysis of Genome Evolution and Function, University of Toronto, ON, Canada
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Genome Editing as a Treatment for the Most Prevalent Causative Genes of Autosomal Dominant Retinitis Pigmentosa. Int J Mol Sci 2019; 20:ijms20102542. [PMID: 31126147 PMCID: PMC6567127 DOI: 10.3390/ijms20102542] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Revised: 05/15/2019] [Accepted: 05/22/2019] [Indexed: 02/07/2023] Open
Abstract
: Inherited retinal dystrophies (IRDs) are a clinically and genetically heterogeneous group of diseases with more than 250 causative genes. The most common form is retinitis pigmentosa. IRDs lead to vision impairment for which there is no universal cure. Encouragingly, a first gene supplementation therapy has been approved for an autosomal recessive IRD. However, for autosomal dominant IRDs, gene supplementation therapy is not always pertinent because haploinsufficiency is not the only cause. Disease-causing mechanisms are often gain-of-function or dominant-negative, which usually require alternative therapeutic approaches. In such cases, genome-editing technology has raised hopes for treatment. Genome editing could be used to i) invalidate both alleles, followed by supplementation of the wild type gene, ii) specifically invalidate the mutant allele, with or without gene supplementation, or iii) to correct the mutant allele. We review here the most prevalent genes causing autosomal dominant retinitis pigmentosa and the most appropriate genome-editing strategy that could be used to target their different causative mutations.
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25
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Perche O, Felgerolle C, Ardourel M, Bazinet A, Pâris A, Rossignol R, Meyer-Dilhet G, Mausset-Bonnefont AL, Hébert B, Laurenceau D, Montécot-Dubourg C, Menuet A, Bizot JC, Pichon J, Ranchon-Cole I, Briault S. Early Retinal Defects in Fmr1-/y Mice: Toward a Critical Role of Visual Dys-Sensitivity in the Fragile X Syndrome Phenotype? Front Cell Neurosci 2018; 12:96. [PMID: 29681800 PMCID: PMC5897671 DOI: 10.3389/fncel.2018.00096] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/22/2018] [Indexed: 12/29/2022] Open
Abstract
Fragile X Syndrome (FXS) is caused by a deficiency in Fragile X Mental Retardation Protein (FMRP) leading to global sensorial abnormalities, among which visual defects represent a critical part. These visual defects are associated with cerebral neuron immaturity especially in the primary visual cortex. However, we recently demonstrated that retinas of adult Fmr1−/y mice, the FXS murine model, present molecular, cellular and functional alterations. However, no data are currently available on the evolution pattern of such defects. As retinal stimulation through Eye Opening (EO) is a crucial signal for the cerebral visual system maturation, we questioned the precocity of molecular and functional retinal phenotype. To answer this question, we studied the retinal molecular phenotype of Fmr1−/y mice before EO until adult age and the consequences of the retinal loss of Fmrp on retinal function in young and adult mice. We showed that retinal molecular defects are present before EO and remain stable at adult age, leading to electrophysiological impairments without any underlying structural changes. We underlined that loss of Fmrp leads to a wide range of defects in the retina, settled even before EO. Our work demonstrates a critical role of the sensorial dysfunction in the Fmr1−/y mice overall phenotype, and provides evidence that altered peripheral perception is a component of the sensory processing defect in FXS conditions.
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Affiliation(s)
- Olivier Perche
- Genetic Department, Centre Hospitalier Régional d'Orléans, Orléans, France.,UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Chloé Felgerolle
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Maryvonne Ardourel
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Audrey Bazinet
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Arnaud Pâris
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Rafaëlle Rossignol
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Géraldine Meyer-Dilhet
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | | | - Betty Hébert
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - David Laurenceau
- Genetic Department, Centre Hospitalier Régional d'Orléans, Orléans, France
| | - Céline Montécot-Dubourg
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Arnaud Menuet
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | | | - Jacques Pichon
- UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Isabelle Ranchon-Cole
- Laboratory of Sensorial Biophysical, INSERM UMR1107 Equipe Biophysique Neurosensorielle, University of Clermont 1, Clermont-Ferrand, France
| | - Sylvain Briault
- Genetic Department, Centre Hospitalier Régional d'Orléans, Orléans, France.,UMR7355, Immunologie et Neurogénétique Expérimentales et Moléculaires (INEM), Centre National de la Recherche Scientifique, Orléans, France.,Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
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26
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C8ORF37 Is Required for Photoreceptor Outer Segment Disc Morphogenesis by Maintaining Outer Segment Membrane Protein Homeostasis. J Neurosci 2018; 38:3160-3176. [PMID: 29440555 DOI: 10.1523/jneurosci.2964-17.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Revised: 01/30/2018] [Accepted: 02/05/2018] [Indexed: 01/09/2023] Open
Abstract
C8ORF37 is a causative gene for three different clinical forms of incurable retinal degeneration. However, the completely unknown function of C8ORF37 limits our understanding of the pathogenicity of C8ORF37 mutations. Here, we performed a comprehensive phenotypic characterization of a C8orf37 KO mouse line, generated using CRISPR/Cas9 technology. Both C8orf37 KO male and female mice exhibited progressive and simultaneous degeneration of rod and cone photoreceptors but no non-ocular phenotypes. The major ultrastructural feature of C8orf37 KO photoreceptors was massive disorganization of the outer segment (OS) membrane discs starting from the onset of disc morphogenesis during development. At the molecular level, the amounts of multiple OS-specific membrane proteins, including proteins involved in membrane disc organization, were reduced, although these proteins were targeted normally to the OS. Considering the distribution of C8ORF37 throughout the photoreceptor cell body, the normal structure of the KO photoreceptor connecting cilium, and the absence of defects in other ciliary organs of the KO mice, our findings do not support the previous notion that C8ORF37 was a ciliary protein. Because C8ORF37 is absent in the photoreceptor OS, C8ORF37 may participate in the secretory pathway of OS membrane proteins in the photoreceptor cell body and thus maintain the homeostasis of these proteins. This study established a valid animal model for future therapeutic studies of C8ORF37-associated retinal degeneration. This study also shed new light on the role of C8ORF37 in photoreceptors and on the pathogenic mechanism underlying retinal degeneration caused by C8ORF37 mutations.SIGNIFICANCE STATEMENT Inherited retinal degeneration is a group of incurable conditions with poorly understood underlying molecular mechanisms. We investigated C8ORF37, a causative gene for three retinal degenerative conditions: retinitis pigmentosa, cone-rod dystrophy, and Bardet-Biedl syndrome. C8ORF37 encodes a protein with no known functional domains and thus its biological function is unpredictable. We knocked out the C8ORF37 ortholog in mice, which resulted in a retinal phenotype similar to that observed in patients. We further demonstrated that C8ORF37 is required for photoreceptor outer segment disc formation and alignment, a process that is critical for photoreceptor function and survival. This study advances our understanding of the pathogenesis of retinal degeneration and establishes a valuable mouse model for future therapeutic development.
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27
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Feehan JM, Chiu CN, Stanar P, Tam BM, Ahmed SN, Moritz OL. Modeling Dominant and Recessive Forms of Retinitis Pigmentosa by Editing Three Rhodopsin-Encoding Genes in Xenopus Laevis Using Crispr/Cas9. Sci Rep 2017; 7:6920. [PMID: 28761125 PMCID: PMC5537283 DOI: 10.1038/s41598-017-07153-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 06/27/2017] [Indexed: 11/11/2022] Open
Abstract
The utility of Xenopus laevis, a common research subject for developmental biology, retinal physiology, cell biology, and other investigations, has been limited by lack of a robust gene knockout or knock-down technology. Here we describe manipulation of the X. laevis genome using CRISPR/Cas9 to model the human disorder retinitis pigmentosa, and to introduce point mutations or exogenous DNA sequences. We introduced and characterized in-frame and out-of-frame insertions and deletions in three genes encoding rhodopsin by co-injection of Cas9 mRNA, eGFP mRNA, and single guide RNAs into fertilized eggs. Deletions were characterized by direct sequencing and cloning; phenotypes were assessed by assays of rod opsin in retinal extracts, and confocal microscopy of cryosectioned and immunolabeled contralateral eyes. We obtained germline transmission of editing to F1 offspring. In-frame deletions frequently caused dominant retinal degeneration associated with rhodopsin biosynthesis defects, while frameshift phenotypes were consistent with knockout. We inserted eGFP or point mutations into rhodopsin genes by co-injection of repair fragments with homology to the Cas9 target sites. Our techniques can produce high frequency gene editing in X. laevis, permitting analysis in the F0 generation, and advancing the utility of X. laevis as a subject for biological research and disease modeling.
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Affiliation(s)
- Joanna M Feehan
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9
- The Sainsbury Laboratory, Colney Ln, Norwich Research Park, Norwich, Norfolk, UK, NR4 7UH
| | - Colette N Chiu
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9
| | - Paloma Stanar
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9
| | - Beatrice M Tam
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9
| | - Sheikh N Ahmed
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9
| | - Orson L Moritz
- Department of Ophthalmology and Visual Sciences, University of British Columbia, Vancouver, British Columbia, Canada, V5Z 3N9.
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Maturation arrest in early postnatal sensory receptors by deletion of the miR-183/96/182 cluster in mouse. Proc Natl Acad Sci U S A 2017; 114:E4271-E4280. [PMID: 28484004 DOI: 10.1073/pnas.1619442114] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The polycistronic miR-183/96/182 cluster is preferentially and abundantly expressed in terminally differentiating sensory epithelia. To clarify its roles in the terminal differentiation of sensory receptors in vivo, we deleted the entire gene cluster in mouse germline through homologous recombination. The miR-183/96/182 null mice display impairment of the visual, auditory, vestibular, and olfactory systems, attributable to profound defects in sensory receptor terminal differentiation. Maturation of sensory receptor precursors is delayed, and they never attain a fully differentiated state. In the retina, delay in up-regulation of key photoreceptor genes underlies delayed outer segment elongation and possibly mispositioning of cone nuclei in the retina. Incomplete maturation of photoreceptors is followed shortly afterward by early-onset degeneration. Cell biologic and transcriptome analyses implicate dysregulation of ciliogenesis, nuclear translocation, and an epigenetic mechanism that may control timing of terminal differentiation in developing photoreceptors. In both the organ of Corti and the vestibular organ, impaired terminal differentiation manifests as immature stereocilia and kinocilia on the apical surface of hair cells. Our study thus establishes a dedicated role of the miR-183/96/182 cluster in driving the terminal differentiation of multiple sensory receptor cells.
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29
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Wensel TG, Zhang Z, Anastassov IA, Gilliam JC, He F, Schmid MF, Robichaux MA. Structural and molecular bases of rod photoreceptor morphogenesis and disease. Prog Retin Eye Res 2016; 55:32-51. [PMID: 27352937 PMCID: PMC5112133 DOI: 10.1016/j.preteyeres.2016.06.002] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 06/14/2016] [Accepted: 06/20/2016] [Indexed: 12/15/2022]
Abstract
The rod cell has an extraordinarily specialized structure that allows it to carry out its unique function of detecting individual photons of light. Both the structural features of the rod and the metabolic processes required for highly amplified light detection seem to have rendered the rod especially sensitive to structural and metabolic defects, so that a large number of gene defects are primarily associated with rod cell death and give rise to blinding retinal dystrophies. The structures of the rod, especially those of the sensory cilium known as the outer segment, have been the subject of structural, biochemical, and genetic analysis for many years, but the molecular bases for rod morphogenesis and for cell death in rod dystrophies are still poorly understood. Recent developments in imaging technology, such as cryo-electron tomography and super-resolution fluorescence microscopy, in gene sequencing technology, and in gene editing technology are rapidly leading to new breakthroughs in our understanding of these questions. A summary is presented of our current understanding of selected aspects of these questions, highlighting areas of uncertainty and contention as well as recent discoveries that provide new insights. Examples of structural data from emerging imaging technologies are presented.
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Affiliation(s)
- Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.
| | - Zhixian Zhang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Ivan A Anastassov
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Jared C Gilliam
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Feng He
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael F Schmid
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
| | - Michael A Robichaux
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA
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30
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Protein stabilization improves STAT3 function in autosomal dominant hyper-IgE syndrome. Blood 2016; 128:3061-3072. [PMID: 27799162 DOI: 10.1182/blood-2016-02-702373] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Accepted: 10/19/2016] [Indexed: 12/17/2022] Open
Abstract
Autosomal dominant hyper-IgE syndrome (AD-HIES) is caused by dominant-negative mutations in STAT3; however, the molecular basis for mutant STAT3 allele dysfunction is unclear and treatment remains supportive. We hypothesized that AD-HIES mutations decrease STAT3 protein stability and that mutant STAT3 activity can be improved by agents that increase chaperone protein activity. We used computer modeling to characterize the effect of STAT3 mutations on protein stability. We measured STAT3 protein half-life (t1/2) and determined levels of STAT3 phosphorylated on tyrosine (Y) 705 (pY-STAT3) and mRNA levels of STAT3 gene targets in Epstein-Barr virus-transformed B (EBV) cells, human peripheral blood mononuclear cells (PBMCs), and mouse splenocytes incubated without or with chaperone protein modulators-HSF1A, a small-molecule TRiC modulator, or geranylgeranylacetone (GGA), a drug that upregulates heat shock protein (HSP) 70 and HSP90. Computer modeling predicted that 81% of AD-HIES mutations are destabilizing. STAT3 protein t1/2 in EBV cells from AD-HIES patients with destabilizing STAT3 mutations was markedly reduced. Treatment of EBV cells containing destabilizing STAT3 mutations with either HSF1A or GGA normalized STAT3 t1/2, increased pY-STAT3 levels, and increased mRNA levels of STAT3 target genes up to 79% of control. In addition, treatment of human PBMCs or mouse splenocytes containing destabilizing STAT3 mutations with either HSF1A or GGA increased levels of cytokine-activated pY-STAT3 within human CD4+ and CD8+ T cells and numbers of IL-17-producing CD4+ mouse splenocytes, respectively. Thus, most AD-HIES STAT3 mutations are destabilizing; agents that modulate chaperone protein function improve STAT3 stability and activity in T cells and may provide a specific treatment.
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31
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Rex TS, Kasmala L, Bond WS, de Lucas Cerrillo AM, Wynn K, Lewin AS. Erythropoietin Slows Photoreceptor Cell Death in a Mouse Model of Autosomal Dominant Retinitis Pigmentosa. PLoS One 2016; 11:e0157411. [PMID: 27299810 PMCID: PMC4907422 DOI: 10.1371/journal.pone.0157411] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 05/27/2016] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To test the efficacy of systemic gene delivery of a mutant form of erythropoietin (EPO-R76E) that has attenuated erythropoietic activity, in a mouse model of autosomal dominant retinitis pigmentosa. METHODS Ten-day old mice carrying one copy of human rhodopsin with the P23H mutation and both copies of wild-type mouse rhodopsin (hP23H RHO+/-,mRHO+/+) were injected into the quadriceps with recombinant adeno-associated virus (rAAV) carrying either enhanced green fluorescent protein (eGFP) or EpoR76E. Visual function (electroretinogram) and retina structure (optical coherence tomography, histology, and immunohistochemistry) were assessed at 7 and 12 months of age. RESULTS The outer nuclear layer thickness decreased over time at a slower rate in rAAV.EpoR76E treated as compared to the rAAV.eGFP injected mice. There was a statistically significant preservation of the electroretinogram at 7, but not 12 months of age. CONCLUSIONS Systemic EPO-R76E slows death of the photoreceptors and vision loss in hP23H RHO+/-,mRHO+/+ mice. Treatment with EPO-R76E may widen the therapeutic window for retinal degeneration patients by increasing the number of viable cells. Future studies might investigate if co-treatment with EPO-R76E and gene replacement therapy is more effective than gene replacement therapy alone.
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Affiliation(s)
- Tonia S. Rex
- Vanderbilt Eye Institute, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States of America
| | - Lorraine Kasmala
- Vanderbilt Eye Institute, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States of America
| | - Wesley S. Bond
- Vanderbilt Eye Institute, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States of America
| | - Ana M. de Lucas Cerrillo
- Vanderbilt Eye Institute, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States of America
| | - Kristi Wynn
- Vanderbilt Eye Institute, Vanderbilt Brain Institute, Vanderbilt University, Nashville, TN 37232, United States of America
| | - Alfred S. Lewin
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL 32608, United States of America
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32
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Goldberg AFX, Moritz OL, Williams DS. Molecular basis for photoreceptor outer segment architecture. Prog Retin Eye Res 2016; 55:52-81. [PMID: 27260426 DOI: 10.1016/j.preteyeres.2016.05.003] [Citation(s) in RCA: 122] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 05/27/2016] [Accepted: 05/29/2016] [Indexed: 01/11/2023]
Abstract
To serve vision, vertebrate rod and cone photoreceptors must detect photons, convert the light stimuli into cellular signals, and then convey the encoded information to downstream neurons. Rods and cones are sensory neurons that each rely on specialized ciliary organelles to detect light. These organelles, called outer segments, possess elaborate architectures that include many hundreds of light-sensitive membranous disks arrayed one atop another in precise register. These stacked disks capture light and initiate the chain of molecular and cellular events that underlie normal vision. Outer segment organization is challenged by an inherently dynamic nature; these organelles are subject to a renewal process that replaces a significant fraction of their disks (up to ∼10%) on a daily basis. In addition, a broad range of environmental and genetic insults can disrupt outer segment morphology to impair photoreceptor function and viability. In this chapter, we survey the major progress that has been made for understanding the molecular basis of outer segment architecture. We also discuss key aspects of organelle lipid and protein composition, and highlight distributions, interactions, and potential structural functions of key OS-resident molecules, including: kinesin-2, actin, RP1, prominin-1, protocadherin 21, peripherin-2/rds, rom-1, glutamic acid-rich proteins, and rhodopsin. Finally, we identify key knowledge gaps and challenges that remain for understanding how normal outer segment architecture is established and maintained.
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Affiliation(s)
- Andrew F X Goldberg
- Eye Research Institute, Oakland University, 417 Dodge Hall, Rochester, MI, 48309, USA.
| | - Orson L Moritz
- Department of Ophthalmology & Visual Sciences, University of British Columbia, Vancouver, BC, Canada
| | - David S Williams
- Department of Ophthalmology and Jules Stein Eye Institute, Department of Neurobiology, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
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33
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Gragg M, Kim TG, Howell S, Park PSH. Wild-type opsin does not aggregate with a misfolded opsin mutant. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1850-9. [PMID: 27117643 DOI: 10.1016/j.bbamem.2016.04.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Revised: 04/06/2016] [Accepted: 04/13/2016] [Indexed: 10/21/2022]
Affiliation(s)
- Megan Gragg
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Tae Gyun Kim
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Scott Howell
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA
| | - P S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, OH 44106, USA.
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34
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Murray SF, Jazayeri A, Matthes MT, Yasumura D, Yang H, Peralta R, Watt A, Freier S, Hung G, Adamson PS, Guo S, Monia BP, LaVail MM, McCaleb ML. Allele-Specific Inhibition of Rhodopsin With an Antisense Oligonucleotide Slows Photoreceptor Cell Degeneration. Invest Ophthalmol Vis Sci 2016; 56:6362-75. [PMID: 26436889 DOI: 10.1167/iovs.15-16400] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE To preserve photoreceptor cell structure and function in a rodent model of retinitis pigmentosa with P23H rhodopsin by selective inhibition of the mutant rhodopsin allele using a second generation antisense oligonucleotide (ASO). METHODS Wild-type mice and rats were treated with ASO by intravitreal (IVT) injection and rhodopsin mRNA and protein expression were measured. Transgenic rats expressing the murine P23H rhodopsin gene (P23H transgenic rat Line 1) were administered either a mouse-specific P23H ASO or a control ASO. The contralateral eye was injected with PBS and used as a comparator control. Electroretinography (ERG) measurements and analyses of the retinal outer nuclear layer were conducted and correlated with rhodopsin mRNA levels. RESULTS Rhodopsin mRNA and protein expression was reduced after a single ASO injection in wild-type mice with a rhodopsin-specific ASO. Transgenic rat eyes that express a murine P23H rhodopsin gene injected with a murine P23H ASO had a 181 ± 39% better maximum amplitude response (scotopic a-wave) as compared with contralateral PBS-injected eyes; the response in control ASO eyes was not significantly different from comparator contralateral eyes. Morphometric analysis of the outer nuclear layer showed a significantly thicker nuclear layer in eyes injected with murine P23H ASO (18%) versus contralateral PBS-injected eyes. CONCLUSIONS Allele-specific ASO-mediated knockdown of mutant P23H rhodopsin expression slowed the rate of photoreceptor degeneration and preserved the function of photoreceptor cells in eyes of the P23H rhodopsin transgenic rat. Our data indicate that ASO treatment is a potentially effective therapy for the treatment of retinitis pigmentosa.
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Affiliation(s)
- Susan F Murray
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Ali Jazayeri
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Michael T Matthes
- University of California at San Francisco School of Medicine, Beckman Vision Center, San Francisco, California, United States
| | - Douglas Yasumura
- University of California at San Francisco School of Medicine, Beckman Vision Center, San Francisco, California, United States
| | - Haidong Yang
- University of California at San Francisco School of Medicine, Beckman Vision Center, San Francisco, California, United States
| | | | - Andy Watt
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Sue Freier
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Gene Hung
- Isis Pharmaceuticals Carlsbad, California, United States
| | | | - Shuling Guo
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Brett P Monia
- Isis Pharmaceuticals Carlsbad, California, United States
| | - Matthew M LaVail
- University of California at San Francisco School of Medicine, Beckman Vision Center, San Francisco, California, United States
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Roman-Sanchez R, Wensel TG, Wilson JH. Nonsense mutations in the rhodopsin gene that give rise to mild phenotypes trigger mRNA degradation in human cells by nonsense-mediated decay. Exp Eye Res 2015; 145:444-449. [PMID: 26416182 DOI: 10.1016/j.exer.2015.09.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Revised: 08/20/2015] [Accepted: 09/22/2015] [Indexed: 02/02/2023]
Abstract
Eight different nonsense mutations in the human rhodopsin gene cause retinitis pigmentosa (RP), an inherited degenerative disease of the retina that can lead to complete blindness. Although all these nonsense mutations lead to premature termination codons (PTCs) in rhodopsin mRNA, some display dominant inheritance, while others are recessive. Because nonsense-mediated decay (NMD) can degrade mRNAs containing PTCs and modulate the inheritance patterns of genetic diseases, we asked whether any of the nonsense mutations in the rhodopsin gene generated mRNAs that were susceptible to degradation by NMD. We hypothesized that nonsense mutations that caused mild RP phenotypes would trigger NMD, whereas those that did not engage NMD would cause more severe RP phenotypes-presumably due to the toxicity of the truncated protein. To test our hypothesis, we transfected human rhodopsin nonsense mutants into HEK293 and HT1080 human cells and measured transcript levels by qRT-PCR. In both cell lines, rhodopsin mutations Q64X and Q344X, which cause severe phenotypes that are dominantly inherited, yielded the same levels of rhodopsin mRNA as wild type. By contrast, rhodopsin mutations W161X and E249X, which cause recessive RP, showed decreased rhodopsin mRNA levels, consistent with NMD. Rhodopsin mutant Y136X, a dominant mutation that causes late-onset RP with a very mild pathology, also gave lower mRNA levels. Treatment of cells with Wortmannin, an inhibitor of NMD, eliminated the degradation of Y136X, W161X, and E249X rhodopsin mRNAs. These results suggest that NMD modulates the severity of RP in patients with nonsense mutations in the rhodopsin gene.
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Affiliation(s)
- Ramon Roman-Sanchez
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Theodore G Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - John H Wilson
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
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Rakshit T, Park PSH. Impact of reduced rhodopsin expression on the structure of rod outer segment disc membranes. Biochemistry 2015; 54:2885-94. [PMID: 25881629 DOI: 10.1021/acs.biochem.5b00003] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Rhodopsin is the light receptor embedded in rod outer segment (ROS) disc membranes of photoreceptor cells that initiates vision via phototransduction. The relationship between rhodopsin expression and the formation of membrane structures in the ROS is unclear but important to better understand both normal function and pathological conditions. To determine the impact of reduced rhodopsin expression on the structure of ROS discs and the supramolecular organization of rhodopsin, ROS disc membrane samples from heterozygous rhodopsin knockout mice were examined by atomic force microscopy. Similar to rhodopsin in wild-type mice, rhodopsin formed nanodomains in ROS disc membranes of heterozygous knockout mice. The reduced rhodopsin expression in heterozygous knockout mice resulted in ROS disc membranes that were smaller compared to those in wild-type mice at all ages tested. Changes in ROS disc membrane properties were observed between 4 and 6 weeks of age in heterozygous knockout mice that were not present in age-matched wild-type mice. In 4 week old mice, the number and density of rhodopsin in ROS disc membranes was lower than that in age-matched wild-type mice. In contrast, 6 and 8 week old mice had more rhodopsin molecules present in disc membranes compared to 4 week old mice, which resulted in rhodopsin densities similar to those found in age-matched wild-type mice. Thus, mechanisms appear to be present that maintain a constant density of rhodopsin within ROS disc membranes even when reducing the expression of the light receptor by about half. These adaptive mechanisms, however, only occur after 4 weeks of age.
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Affiliation(s)
- Tatini Rakshit
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Paul S-H Park
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio 44106, United States
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Nucleotide bound to rab11a controls localization in rod cells but not interaction with rhodopsin. J Neurosci 2014; 34:14854-63. [PMID: 25378153 DOI: 10.1523/jneurosci.1943-14.2014] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Precise vectorial transport of rhodopsin is essential for rod photoreceptor health and function. Mutations that truncate or extend the C terminus of rhodopsin disrupt this transport, and lead to retinal degeneration and blindness in human patients and in mouse models. Here we show that such mutations disrupt the binding of rhodopsin to the small GTPase rab11a. The rhodopsin-rab11a interaction is a direct binding interaction that does not depend on the nucleotide binding state of rab11a. Expression of EGFP-rab11a fusion proteins in Xenopus laevis photoreceptors revealed that the nucleotide binding status of rab11a affects its subcellular localization, with GTP-locked mutants concentrated in the inner segment and GDP-locked mutants concentrated in the outer segment. shRNA-mediated knockdown of rab11a in rods led to shortened outer segments and retinal degeneration. Together, our results show the critical importance of direct rhodopsin-rab11a interactions for the formation and maintenance of vertebrate photoreceptors.
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38
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Palczewski K. Chemistry and biology of the initial steps in vision: the Friedenwald lecture. Invest Ophthalmol Vis Sci 2014; 55:6651-72. [PMID: 25338686 DOI: 10.1167/iovs.14-15502] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Visual transduction is the process in the eye whereby absorption of light in the retina is translated into electrical signals that ultimately reach the brain. The first challenge presented by visual transduction is to understand its molecular basis. We know that maintenance of vision is a continuous process requiring the activation and subsequent restoration of a vitamin A-derived chromophore through a series of chemical reactions catalyzed by enzymes in the retina and retinal pigment epithelium (RPE). Diverse biochemical approaches that identified key proteins and reactions were essential to achieve a mechanistic understanding of these visual processes. The three-dimensional arrangements of these enzymes' polypeptide chains provide invaluable insights into their mechanisms of action. A wealth of information has already been obtained by solving high-resolution crystal structures of both rhodopsin and the retinoid isomerase from pigment RPE (RPE65). Rhodopsin, which is activated by photoisomerization of its 11-cis-retinylidene chromophore, is a prototypical member of a large family of membrane-bound proteins called G protein-coupled receptors (GPCRs). RPE65 is a retinoid isomerase critical for regeneration of the chromophore. Electron microscopy (EM) and atomic force microscopy have provided insights into how certain proteins are assembled to form much larger structures such as rod photoreceptor cell outer segment membranes. A second challenge of visual transduction is to use this knowledge to devise therapeutic approaches that can prevent or reverse conditions leading to blindness. Imaging modalities like optical coherence tomography (OCT) and scanning laser ophthalmoscopy (SLO) applied to appropriate animal models as well as human retinal imaging have been employed to characterize blinding diseases, monitor their progression, and evaluate the success of therapeutic agents. Lately two-photon (2-PO) imaging, together with biochemical assays, are revealing functional aspects of vision at a new molecular level. These multidisciplinary approaches combined with suitable animal models and inbred mutant species can be especially helpful in translating provocative cell and tissue culture findings into therapeutic options for further development in animals and eventually in humans. A host of different approaches and techniques is required for substantial progress in understanding fundamental properties of the visual system.
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Affiliation(s)
- Krzysztof Palczewski
- Department of Pharmacology, Cleveland Center for Membrane and Structural Biology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
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Sandoval IM, Price BA, Gross AK, Chan F, Sammons JD, Wilson JH, Wensel TG. Abrupt onset of mutations in a developmentally regulated gene during terminal differentiation of post-mitotic photoreceptor neurons in mice. PLoS One 2014; 9:e108135. [PMID: 25264759 PMCID: PMC4180260 DOI: 10.1371/journal.pone.0108135] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 08/18/2014] [Indexed: 11/22/2022] Open
Abstract
For sensitive detection of rare gene repair events in terminally differentiated photoreceptors, we generated a knockin mouse model by replacing one mouse rhodopsin allele with a form of the human rhodopsin gene that causes a severe, early-onset form of retinitis pigmentosa. The human gene contains a premature stop codon at position 344 (Q344X), cDNA encoding the enhanced green fluorescent protein (EGFP) at its 3′ end, and a modified 5′ untranslated region to reduce translation rate so that the mutant protein does not induce retinal degeneration. Mutations that eliminate the stop codon express a human rhodopsin-EGFP fusion protein (hRho-GFP), which can be readily detected by fluorescence microscopy. Spontaneous mutations were observed at a frequency of about one per retina; in every case, they gave rise to single fluorescent rod cells, indicating that each mutation occurred during or after the last mitotic division. Additionally, the number of fluorescent rods did not increase with age, suggesting that the rhodopsin gene in mature rod cells is less sensitive to mutation than it is in developing rods. Thus, there is a brief developmental window, coinciding with the transcriptional activation of the rhodopsin locus, in which somatic mutations of the rhodopsin gene abruptly begin to appear.
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Affiliation(s)
- Ivette M. Sandoval
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, Texas, United States of America
| | - Brandee A. Price
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alecia K. Gross
- Department of Vision Science, University of Alabama Birmingham, Birmingham, Alabama, United States of America
| | - Fung Chan
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, Texas, United States of America
| | - Joshua D. Sammons
- Department of Vision Science, University of Alabama Birmingham, Birmingham, Alabama, United States of America
| | - John H. Wilson
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, Texas, United States of America
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Theodore G. Wensel
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Houston, Texas, United States of America
- * E-mail:
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Rossignol R, Ranchon-Cole I, Pâris A, Herzine A, Perche A, Laurenceau D, Bertrand P, Cercy C, Pichon J, Mortaud S, Briault S, Menuet A, Perche O. Visual sensorial impairments in neurodevelopmental disorders: evidence for a retinal phenotype in Fragile X Syndrome. PLoS One 2014; 9:e105996. [PMID: 25153086 PMCID: PMC4143372 DOI: 10.1371/journal.pone.0105996] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Accepted: 07/25/2014] [Indexed: 01/28/2023] Open
Abstract
Visual sensory impairments are common in Mental Deficiency (MD) and Autism Spectrum Disorder (ASD). These defects are linked to cerebral dysfunction in the visual cortical area characterized by the deregulation of axon growth/guidance and dendrite spine immaturity of neurons. However, visual perception had not been addressed, although the retina is part of the central nervous system with a common embryonic origin. Therefore, we investigated retinal perception, the first event of vision, in a murine model of MD with autistic features. We document that retinal function is altered in Fmr1 KO mice, a model of human Fragile X Syndrome. Indeed, In Fmr1 KO mice had a lower retinal function characterized by a decreased photoreceptors neuron response, due to a 40% decrease in Rhodopsin content and to Rod Outer Segment destabilization. In addition, we observed an alteration of the visual signal transmission between photoreceptors and the inner retina which could be attributed to deregulations of pre- and post- synaptic proteins resulting in retinal neurons synaptic destabilization and to retinal neurons immaturity. Thus, for the first time, we demonstrated that retinal perception is altered in a murine model of MD with autistic features and that there are strong similarities between cerebral and retinal cellular and molecular defects. Our results suggest that both visual perception and integration must be taken into account in assessing visual sensory impairments in MD and ASD.
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Affiliation(s)
- Rafaëlle Rossignol
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Isabelle Ranchon-Cole
- Laboratory of Sensorial Biophysical, University of Clermont 1, Clermont-Ferrand, France
| | - Arnaud Pâris
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Ameziane Herzine
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Astrid Perche
- Genetic Department, Regional Hospital, Orléans, France
| | | | - Pauline Bertrand
- Laboratory of Sensorial Biophysical, University of Clermont 1, Clermont-Ferrand, France
| | - Christine Cercy
- Laboratory of Sensorial Biophysical, University of Clermont 1, Clermont-Ferrand, France
| | - Jacques Pichon
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Stéphane Mortaud
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Sylvain Briault
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
- Genetic Department, Regional Hospital, Orléans, France
| | - Arnaud Menuet
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
| | - Olivier Perche
- UMR7355, CNRS, Orléans, France
- Experimental and Molecular Immunology and Neurogenetics, University of Orléans, Orléans, France
- Genetic Department, Regional Hospital, Orléans, France
- * E-mail:
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Lewin AS, Rossmiller B, Mao H. Gene augmentation for adRP mutations in RHO. Cold Spring Harb Perspect Med 2014; 4:a017400. [PMID: 25037104 DOI: 10.1101/cshperspect.a017400] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Mutations in the gene for rhodopsin, RHO, cause autosomal dominant retinitis pigmentosa, a disease characterized by death of rod photoreceptor cells. At the end stage, when most rods are gone, cones die too, taking central vision with them. One goal of gene therapy, therefore, is to preserve central vision by promoting rod survival in the vicinity of the macula. Dominance in RHO mutations is associated with two phenomena: interference with the function of normal rhodopsin and intrinsic toxicity of the mutant protein. In the case of interference, increased production of the wild-type protein may be therapeutic, but in the case of toxicity, suppression of the mutant protein may also be needed. RHO augmentation has made use of advances in gene delivery to the retina using adeno-associated virus (AAV). Several strategies have been developed for suppression of rhodopsin expression, but because of the heterogeneity of RHO mutations they are not specific for the mutant allele: They suppress both mutant and wild-type RHO. Experiments in autosomal dominant retinitis pigmentosa (adRP) mouse models suggest that both RHO augmentation and supplementation plus suppression preserve the survival of rod cells.
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Affiliation(s)
- Alfred S Lewin
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida 32610
| | - Brian Rossmiller
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida 32610
| | - Haoyu Mao
- Department of Molecular Genetics and Microbiology, University of Florida College of Medicine, Gainesville, Florida 32610
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Chakraborty D, Conley SM, Al-Ubaidi MR, Naash MI. Initiation of rod outer segment disc formation requires RDS. PLoS One 2014; 9:e98939. [PMID: 24897172 PMCID: PMC4045911 DOI: 10.1371/journal.pone.0098939] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2014] [Accepted: 05/08/2014] [Indexed: 11/23/2022] Open
Abstract
Rod outer segment (OS) morphogenesis involves assembly of flattened discs circumscribed by a hairpin-like rim, however, the role of the rim and rim proteins such as retinal degeneration slow (RDS) and its homologue rod OS membrane protein-1 (ROM-1) in this process remains unclear. Here we show that without RDS, no disc/OS formation occurs, while without rhodopsin, small OS structures form containing aligned nascent discs. In the absence of both rhodopsin and RDS, RDS-associated degeneration is slowed, and ROM-1 is stabilized and trafficked to the OS. These animals (rho-/-/rds-/-) exhibit OSs slightly better than those lacking only RDS, but still without signs of disc formation. These results clearly demonstrate that OS morphogenesis is initiated by RDS-mediated rim formation, a process ROM-1 cannot recapitulate, with subsequent disc growth mediated by rhodopsin. The critical role of RDS in this process helps explain why photoreceptors are so sensitive to varied RDS levels, and why mutations in RDS cause debilitating retinal disease.
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Affiliation(s)
- Dibyendu Chakraborty
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Shannon M. Conley
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Muayyad R. Al-Ubaidi
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
| | - Muna I. Naash
- Department of Cell Biology, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States of America
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Parfitt DA, Aguila M, McCulley CH, Bevilacqua D, Mendes HF, Athanasiou D, Novoselov SS, Kanuga N, Munro PM, Coffey PJ, Kalmar B, Greensmith L, Cheetham ME. The heat-shock response co-inducer arimoclomol protects against retinal degeneration in rhodopsin retinitis pigmentosa. Cell Death Dis 2014; 5:e1236. [PMID: 24853414 PMCID: PMC4047904 DOI: 10.1038/cddis.2014.214] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 04/04/2014] [Accepted: 04/09/2014] [Indexed: 01/04/2023]
Abstract
Retinitis pigmentosa (RP) is a group of inherited diseases that cause blindness due to the progressive death of rod and cone photoreceptors in the retina. There are currently no effective treatments for RP. Inherited mutations in rhodopsin, the light-sensing protein of rod photoreceptor cells, are the most common cause of autosomal-dominant RP. The majority of mutations in rhodopsin, including the common P23H substitution, lead to protein misfolding, which is a feature in many neurodegenerative disorders. Previous studies have shown that upregulating molecular chaperone expression can delay disease progression in models of neurodegeneration. Here, we have explored the potential of the heat-shock protein co-inducer arimoclomol to ameliorate rhodopsin RP. In a cell model of P23H rod opsin RP, arimoclomol reduced P23H rod opsin aggregation and improved viability of mutant rhodopsin-expressing cells. In P23H rhodopsin transgenic rat models, pharmacological potentiation of the stress response with arimoclomol improved electroretinogram responses and prolonged photoreceptor survival, as assessed by measuring outer nuclear layer thickness in the retina. Furthermore, treated animal retinae showed improved photoreceptor outer segment structure and reduced rhodopsin aggregation compared with vehicle-treated controls. The heat-shock response (HSR) was activated in P23H retinae, and this was enhanced with arimoclomol treatment. Furthermore, the unfolded protein response (UPR), which is induced in P23H transgenic rats, was also enhanced in the retinae of arimoclomol-treated animals, suggesting that arimoclomol can potentiate the UPR as well as the HSR. These data suggest that pharmacological enhancement of cellular stress responses may be a potential treatment for rhodopsin RP and that arimoclomol could benefit diseases where ER stress is a factor.
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Affiliation(s)
- D A Parfitt
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - M Aguila
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - C H McCulley
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - D Bevilacqua
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - H F Mendes
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - D Athanasiou
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - S S Novoselov
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - N Kanuga
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - P M Munro
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - P J Coffey
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
| | - B Kalmar
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
| | - L Greensmith
- Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, London, UK
- MRC Centre for Neuromuscular Diseases, UCL Institute of Neurology, Queen Square, London, UK
| | - M E Cheetham
- Ocular Biology and Therapeutics, UCL Institute of Ophthalmology, London, UK
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Scott PA, Fernandez de Castro JP, Kaplan HJ, McCall MA. A Pro23His mutation alters prenatal rod photoreceptor morphology in a transgenic swine model of retinitis pigmentosa. Invest Ophthalmol Vis Sci 2014; 55:2452-9. [PMID: 24618321 DOI: 10.1167/iovs.13-13723] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
PURPOSE Functional studies have detected deficits in retinal signaling in asymptomatic children from families with inherited autosomal dominant retinitis pigmentosa (RP). Whether retinal abnormalities are present earlier during gestation or shortly after birth in a subset of children with autosomal dominant RP is unknown and no appropriate animal RP model possessing visual function at birth has been available to examine this possibility. In a recently developed transgenic P23H (TgP23H) rhodopsin swine model of RP, we tracked changes in pre- and early postnatal retinal morphology, as well as early postnatal retinal function. METHODS Domestic swine inseminated with semen from a TgP23H miniswine founder produced TgP23H hybrid and wild type (Wt) littermates. Outer retinal morphology was assessed at light and electron microscopic levels between embryonic (E) and postnatal (P) day E85 to P3. Retinal function was evaluated using the full field electroretinogram at P3. RESULTS Embryonic TgP23H rod photoreceptors are malformed and their rhodopsin expression pattern is abnormal. Consistent with morphological abnormalities, rod-driven function is absent at P3. In contrast, TgP23H and Wt cone photoreceptor morphology (E85-P3) and cone-driven retinal function (P3) are similar. CONCLUSIONS Prenatal expression of mutant rhodopsin alters the normal morphological and functional development of rod photoreceptors in TgP23H swine embryos. Despite this significant change, cone photoreceptors are unaffected. Human infants with similarly aggressive RP might never have rod vision, although cone vision would be unaffected. Such aggressive forms of RP in preverbal children would require early intervention to delay or prevent functional blindness.
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Affiliation(s)
- Patrick A Scott
- Department of Ophthalmology and Visual Sciences, University of Louisville, Louisville, Kentucky, United States
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Adekeye A, Haeri M, Solessio E, Knox BE. Ablation of the proapoptotic genes CHOP or Ask1 does not prevent or delay loss of visual function in a P23H transgenic mouse model of retinitis pigmentosa. PLoS One 2014; 9:e83871. [PMID: 24523853 PMCID: PMC3921110 DOI: 10.1371/journal.pone.0083871] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2013] [Accepted: 11/08/2013] [Indexed: 11/19/2022] Open
Abstract
The P23H mutation in rhodopsin (Rho(P23H)) is a prevalent cause of autosomal dominant retinitis pigmentosa. We examined the role of the ER stress proteins, Chop and Ask1, in regulating the death of rod photoreceptors in a mouse line harboring the Rho(P23H) rhodopsin transgene (GHL(+)). We used knockout mice models to determine whether Chop and Ask1 regulate rod survival or retinal degeneration. Electrophysiological recordings showed similar retinal responses and sensitivities for GHL(+), GHL(+)/Chop(-/-) and GHL(+)/Ask1(-/-) animals between 4-28 weeks, by which time all three mouse lines exhibited severe loss of retinal function. Histologically, ablation of Chop and Ask1 did not rescue photoreceptor loss in young animals. However, in older mice, a regional protective effect was observed in the central retina of GHL(+)/Chop(-/-) and GHL(+)/Ask1(-/-), a region that was severely degenerated in GHL(+) mice. Our results show that in the presence of the Rho(P23H) transgene, the rate of decline in retinal sensitivity is similar in Chop or Ask1 ablated and wild-type retinas, suggesting that these proteins do not play a major role during the acute phase of photoreceptor loss in GHL(+) mice. Instead they may be involved in regulating secondary pathological responses such as inflammation that are upregulated during later stages of disease progression.
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Affiliation(s)
- Adeseye Adekeye
- Departments of Neuroscience & Physiology, Biochemistry & Molecular Biology and Ophthalmology, Center for Vision Research, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Mohammad Haeri
- Departments of Neuroscience & Physiology, Biochemistry & Molecular Biology and Ophthalmology, Center for Vision Research, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Eduardo Solessio
- Departments of Neuroscience & Physiology, Biochemistry & Molecular Biology and Ophthalmology, Center for Vision Research, SUNY Upstate Medical University, Syracuse, New York, United States of America
| | - Barry E. Knox
- Departments of Neuroscience & Physiology, Biochemistry & Molecular Biology and Ophthalmology, Center for Vision Research, SUNY Upstate Medical University, Syracuse, New York, United States of America
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Yadav SP, Hao H, Yang HJ, Kautzmann MAI, Brooks M, Nellissery J, Klocke B, Seifert M, Swaroop A. The transcription-splicing protein NonO/p54nrb and three NonO-interacting proteins bind to distal enhancer region and augment rhodopsin expression. Hum Mol Genet 2013; 23:2132-44. [PMID: 24301678 DOI: 10.1093/hmg/ddt609] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Phototransduction machinery in vertebrate photoreceptors is contained within the membrane discs of outer segments. Daily renewal of 10% of photoreceptor outer segments requires stringent control of gene expression. Rhodopsin constitutes over 90% of the protein in rod discs, and its altered expression or transport is associated with photoreceptor dysfunction and/or death. Two cis-regulatory sequences have been identified upstream of the rhodopsin transcription start site. While the proximal promoter binds to specific transcription factors, including NRL and CRX, the rhodopsin enhancer region (RER) reportedly contributes to precise and high-level expression of rhodopsin in vivo. Here, we report the identification of RER-bound proteins by mass spectrometry. We validate the binding of NonO (p54(nrb)), a protein implicated in coupling transcription to splicing, and three NonO-interacting proteins-hnRNP M, Ywhaz and Ppp1ca. NonO and its interactors can activate rhodopsin promoter in HEK293 cells and function synergistically with NRL and CRX. DNA-binding domain of NonO is critical for rhodopsin promoter activation. Chromatin immunoprecipitation followed by deep sequencing (ChIP-seq) analysis demonstrates high occupancy of NonO at rhodopsin and a subset of phototransduction genes. Furthermore, shRNA knockdown of NonO in mouse retina leads to loss of rhodopsin expression and rod cell death, which can be partially rescued by a C-terminal NonO construct. RNA-seq analysis of the NonO shRNA-treated retina revealed splicing defects and altered expression of genes, specifically those associated with phototransduction. Our studies identify an important contribution of NonO and its interacting modulator proteins in enhancing rod-specific gene expression and controlling rod homeostasis.
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Affiliation(s)
- Sharda P Yadav
- Neurobiology-Neurodegeneration and Repair Laboratory, National Eye Institute, National Institutes of Health, Bethesda, MD 20892, USA
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Dalet FGE, Guadalupe TFJ, María del Carmen CH, Humberto GAC, Antonio SUM. Insights into the structural biology of G-protein coupled receptors impacts drug design for central nervous system neurodegenerative processes. Neural Regen Res 2013; 8:2290-302. [PMID: 25206539 PMCID: PMC4146033 DOI: 10.3969/j.issn.1673-5374.2013.24.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2013] [Accepted: 06/25/2013] [Indexed: 02/05/2023] Open
Abstract
In the last few years, there have been important new insights into the structural biology of G-protein coupled receptors. It is now known that allosteric binding sites are involved in the affinity and selectivity of ligands for G-protein coupled receptors, and that signaling by these receptors involves both G-protein dependent and independent pathways. The present review outlines the physiological and pharmacological implications of this perspective for the design of new drugs to treat disorders of the central nervous system. Specifically, new possibilities are explored in relation to allosteric and orthosteric binding sites on dopamine receptors for the treatment of Parkinson's disease, and on muscarinic receptors for Alzheimer's disease. Future research can seek to identify ligands that can bind to more than one site on the same receptor, or simultaneously bind to two receptors and form a dimer. For example, the design of bivalent drugs that can reach homo/hetero-dimers of D2 dopamine receptor holds promise as a relevant therapeutic strategy for Parkinson's disease. Regarding the treatment of Alzheimer's disease, the design of dualsteric ligands for mono-oligomeric rinic receptors could increase therapeutic effectiveness by generating potent compounds that could activate more than one signaling pathway.
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Affiliation(s)
- Farfán-García Eunice Dalet
- Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico
| | - Trujillo-Ferrara José Guadalupe
- Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico
| | - Castillo-Hernández María del Carmen
- Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico
| | - Guerra-Araiza Christian Humberto
- Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico
| | - Soriano-Ursúa Marvin Antonio
- Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico
- Corresponding author: Soriano-Ursúa Marvin Antonio, Professor/Researcher, Departamento de Fisiología y Sección de Estudios de Posgrado e Investigación, Escuela Superior de Medicina, Instituto Politécnico Nacional. Plan de San Luis y Díaz Mirón s/n, Col. Casco de Santo Tomas, Del. Benito Juárez, Mexico City 11340, Mexico, , (N201304028)
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Aerni-Flessner L, Haeri M, Knox BE, Pignoni F. Can fly photoreceptors lead to treatments for rho ((P23H)) -linked retinitis pigmentosa? J Ophthalmic Vis Res 2013; 8:86-91. [PMID: 23825721 PMCID: PMC3691985] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
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