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Sai H, Ollington B, Rezek FO, Chai N, Lane A, Georgiadis T, Bainbridge J, Michaelides M, Sacristan-Reviriego A, Perdigão PR, Leung A, van der Spuy J. Effective AAV-mediated gene replacement therapy in retinal organoids modeling AIPL1-associated LCA4. MOLECULAR THERAPY. NUCLEIC ACIDS 2024; 35:102148. [PMID: 38439910 PMCID: PMC10910061 DOI: 10.1016/j.omtn.2024.102148] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Accepted: 02/12/2024] [Indexed: 03/06/2024]
Abstract
Biallelic variations in the aryl hydrocarbon receptor interacting protein-like 1 (AIPL1) gene cause Leber congenital amaurosis subtype 4 (LCA4), an autosomal recessive early-onset severe retinal dystrophy that leads to the rapid degeneration of retinal photoreceptors and the severe impairment of sight within the first few years of life. Currently, there is no treatment or cure for AIPL1-associated LCA4. In this study, we investigated the potential of adeno-associated virus-mediated AIPL1 gene replacement therapy in two previously validated human retinal organoid (RO) models of LCA4. We report here that photoreceptor-specific AIPL1 gene replacement therapy, currently being tested in a first-in-human application, effectively rescued molecular features of AIPL1-associated LCA4 in these models. Notably, the loss of retinal phosphodiesterase 6 was rescued and elevated cyclic guanosine monophosphate (cGMP) levels were reduced following treatment. Transcriptomic analysis of untreated and AAV-transduced ROs revealed transcriptomic changes in response to elevated cGMP levels and viral infection, respectively. Overall, this study supports AIPL1 gene therapy as a promising therapeutic intervention for LCA4.
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Affiliation(s)
- Hali Sai
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Bethany Ollington
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Farah O. Rezek
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Niuzheng Chai
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | | | | | - James Bainbridge
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- NIHR Moorfields Biomedical Research Centre, London EC1V 2PD, UK
| | - Michel Michaelides
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- NIHR Moorfields Biomedical Research Centre, London EC1V 2PD, UK
| | - Almudena Sacristan-Reviriego
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Institute of Clinical Trials and Methodology, University College London, London WC1V 6LJ, UK
| | - Pedro R.L. Perdigão
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
- Center for Neuroscience and Cell Biology, University of Coimbra, 3004-504 Coimbra, Portugal
| | - Amy Leung
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Jacqueline van der Spuy
- University College London Institute of Ophthalmology, University College London, London EC1V 9EL, UK
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2
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Yalaz C, Bridges E, Alham NK, Zois CE, Chen J, Bensaad K, Miar A, Pires E, Muschel RJ, McCullagh JSO, Harris AL. Cone photoreceptor phosphodiesterase PDE6H inhibition regulates cancer cell growth and metabolism, replicating the dark retina response. Cancer Metab 2024; 12:5. [PMID: 38350962 PMCID: PMC10863171 DOI: 10.1186/s40170-023-00326-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Accepted: 11/24/2023] [Indexed: 02/15/2024] Open
Abstract
BACKGROUND PDE6H encodes PDE6γ', the inhibitory subunit of the cGMP-specific phosphodiesterase 6 in cone photoreceptors. Inhibition of PDE6, which has been widely studied for its role in light transduction, increases cGMP levels. The purpose of this study is to characterise the role of PDE6H in cancer cell growth. METHODS From an siRNA screen for 487 genes involved in metabolism, PDE6H was identified as a controller of cell cycle progression in HCT116 cells. Role of PDE6H in cancer cell growth and metabolism was studied through the effects of its depletion on levels of cell cycle controllers, mTOR effectors, metabolite levels, and metabolic energy assays. Effect of PDE6H deletion on tumour growth was also studied in a xenograft model. RESULTS PDE6H knockout resulted in an increase of intracellular cGMP levels, as well as changes to the levels of nucleotides and key energy metabolism intermediates. PDE6H knockdown induced G1 cell cycle arrest and cell death and reduced mTORC1 signalling in cancer cell lines. Both knockdown and knockout of PDE6H resulted in the suppression of mitochondrial function. HCT116 xenografts revealed that PDE6H deletion, as well as treatment with the PDE5/6 inhibitor sildenafil, slowed down tumour growth and improved survival, while sildenafil treatment did not have an additive effect on slowing the growth of PDE6γ'-deficient tumours. CONCLUSIONS Our results indicate that the changes in cGMP and purine pools, as well as mitochondrial function which is observed upon PDE6γ' depletion, are independent of the PKG pathway. We show that in HCT116, PDE6H deletion replicates many effects of the dark retina response and identify PDE6H as a new target in preventing cancer cell proliferation and tumour growth.
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Affiliation(s)
- Ceren Yalaz
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK.
| | - Esther Bridges
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Nasullah K Alham
- Department of Engineering Science, Institute of Biomedical Engineering (IBME), University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Christos E Zois
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Jianzhou Chen
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Karim Bensaad
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
| | - Ana Miar
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - Elisabete Pires
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Ruth J Muschel
- Department of Oncology, University of Oxford, Old Road Campus Research Building, Oxford, OX3 7DQ, UK
| | - James S O McCullagh
- Department of Chemistry, University of Oxford, Mansfield Road, Oxford, OX1 3TA, UK
| | - Adrian L Harris
- Molecular Oncology Laboratories, Department of Medical Oncology, John Radcliffe Hospital, Weatherall Institute of Molecular Medicine, University of Oxford, Oxford, OX3 9DS, UK
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3
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Liang Y, Sun X, Duan C, Tang S, Chen J. Application of patient-derived induced pluripotent stem cells and organoids in inherited retinal diseases. Stem Cell Res Ther 2023; 14:340. [PMID: 38012786 PMCID: PMC10683306 DOI: 10.1186/s13287-023-03564-5] [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: 08/29/2023] [Accepted: 11/06/2023] [Indexed: 11/29/2023] Open
Abstract
Inherited retinal diseases (IRDs) can induce severe sight-threatening retinal degeneration and impose a considerable economic burden on patients and society, making efforts to cure blindness imperative. Transgenic animals mimicking human genetic diseases have long been used as a primary research tool to decipher the underlying pathogenesis, but there are still some obvious limitations. As an alternative strategy, patient-derived induced pluripotent stem cells (iPSCs), particularly three-dimensional (3D) organoid technology, are considered a promising platform for modeling different forms of IRDs, including retinitis pigmentosa, Leber congenital amaurosis, X-linked recessive retinoschisis, Batten disease, achromatopsia, and best vitelliform macular dystrophy. Here, this paper focuses on the status of patient-derived iPSCs and organoids in IRDs in recent years concerning disease modeling and therapeutic exploration, along with potential challenges for translating laboratory research to clinical application. Finally, the importance of human iPSCs and organoids in combination with emerging technologies such as multi-omics integration analysis, 3D bioprinting, or microfluidic chip platform are highlighted. Patient-derived retinal organoids may be a preferred choice for more accurately uncovering the mechanisms of human retinal diseases and will contribute to clinical practice.
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Affiliation(s)
- Yuqin Liang
- Aier Eye Institute, Changsha, 410015, China
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Xihao Sun
- Aier Eye Institute, Changsha, 410015, China
- Eye Center of Xiangya Hospital, Central South University, Changsha, 410008, China
| | - Chunwen Duan
- Aier Eye Institute, Changsha, 410015, China
- Changsha Aier Eye Hospital, Changsha, 410015, China
| | - Shibo Tang
- Aier Eye Institute, Changsha, 410015, China.
- Changsha Aier Eye Hospital, Changsha, 410015, China.
| | - Jiansu Chen
- Aier Eye Institute, Changsha, 410015, China.
- Changsha Aier Eye Hospital, Changsha, 410015, China.
- Key Laboratory for Regenerative Medicine, Ministry of Education, Jinan University, Guangzhou, 510632, China.
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4
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Munezero D, Aliff H, Salido E, Saravanan T, Sanzhaeva U, Guan T, Ramamurthy V. HSP90α is needed for the survival of rod photoreceptors and regulates the expression of rod PDE6 subunits. J Biol Chem 2023; 299:104809. [PMID: 37172722 PMCID: PMC10250166 DOI: 10.1016/j.jbc.2023.104809] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 04/19/2023] [Accepted: 04/20/2023] [Indexed: 05/15/2023] Open
Abstract
Heat shock protein 90 (HSP90) is an abundant molecular chaperone that regulates the stability of a small set of proteins essential in various cellular pathways. Cytosolic HSP90 has two closely related paralogs: HSP90α and HSP90β. Due to the structural and sequence similarities of cytosolic HSP90 paralogs, identifying the unique functions and substrates in the cell remains challenging. In this article, we assessed the role of HSP90α in the retina using a novel HSP90α murine knockout model. Our findings show that HSP90α is essential for rod photoreceptor function but was dispensable in cone photoreceptors. In the absence of HSP90α, photoreceptors developed normally. We observed rod dysfunction in HSP90α knockout at 2 months with the accumulation of vacuolar structures, apoptotic nuclei, and abnormalities in the outer segments. The decline in rod function was accompanied by progressive degeneration of rod photoreceptors that was complete at 6 months. The deterioration in cone function and health was a "bystander effect" that followed the degeneration of rods. Tandem mass tag proteomics showed that HSP90α regulates the expression levels of <1% of the retinal proteome. More importantly, HSP90α was vital in maintaining rod PDE6 and AIPL1 cochaperone levels in rod photoreceptor cells. Interestingly, cone PDE6 levels were unaffected. The robust expression of HSP90β paralog in cones likely compensates for the loss of HSP90α. Overall, our study demonstrated the critical need for HSP90α chaperone in the maintenance of rod photoreceptors and showed potential substrates regulated by HSP90α in the retina.
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Affiliation(s)
- Daniella Munezero
- Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, West Virginia, USA; Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA
| | - Hunter Aliff
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Ezequiel Salido
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Thamaraiselvi Saravanan
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Urikhan Sanzhaeva
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Tongju Guan
- Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA
| | - Visvanathan Ramamurthy
- Department of Pharmaceutical and Pharmacological Sciences, West Virginia University, Morgantown, West Virginia, USA; Ophthalmology and Visual Sciences, West Virginia University, Morgantown, West Virginia, USA; Biochemistry and Molecular Medicine, West Virginia University, Morgantown, West Virginia, USA.
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5
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Perdigão PRL, Ollington B, Sai H, Leung A, Sacristan-Reviriego A, van der Spuy J. Retinal Organoids from an AIPL1 CRISPR/Cas9 Knockout Cell Line Successfully Recapitulate the Molecular Features of LCA4 Disease. Int J Mol Sci 2023; 24:ijms24065912. [PMID: 36982987 PMCID: PMC10057647 DOI: 10.3390/ijms24065912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 02/27/2023] [Accepted: 03/07/2023] [Indexed: 03/30/2023] Open
Abstract
Aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) is expressed in photoreceptors where it facilitates the assembly of phosphodiesterase 6 (PDE6) which hydrolyses cGMP within the phototransduction cascade. Genetic variations in AIPL1 cause type 4 Leber congenital amaurosis (LCA4), which presents as rapid loss of vision in early childhood. Limited in vitro LCA4 models are available, and these rely on patient-derived cells harbouring patient-specific AIPL1 mutations. While valuable, the use and scalability of individual patient-derived LCA4 models may be limited by ethical considerations, access to patient samples and prohibitive costs. To model the functional consequences of patient-independent AIPL1 mutations, CRISPR/Cas9 was implemented to produce an isogenic induced pluripotent stem cell line harbouring a frameshift mutation in the first exon of AIPL1. Retinal organoids were generated using these cells, which retained AIPL1 gene transcription, but AIPL1 protein was undetectable. AIPL1 knockout resulted in a decrease in rod photoreceptor-specific PDE6α and β, and increased cGMP levels, suggesting downstream dysregulation of the phototransduction cascade. The retinal model described here provides a novel platform to assess functional consequences of AIPL1 silencing and measure the rescue of molecular features by potential therapeutic approaches targeting mutation-independent pathogenesis.
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Affiliation(s)
- Pedro R L Perdigão
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Bethany Ollington
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Hali Sai
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Amy Leung
- Institute of Ophthalmology, University College London, London EC1V 9EL, UK
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6
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Prodromou C, Aran-Guiu X, Oberoi J, Perna L, Chapple JP, van der Spuy J. HSP70-HSP90 Chaperone Networking in Protein-Misfolding Disease. Subcell Biochem 2023; 101:389-425. [PMID: 36520314 DOI: 10.1007/978-3-031-14740-1_13] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Molecular chaperones and their associated co-chaperones are essential in health and disease as they are key facilitators of protein-folding, quality control and function. In particular, the heat-shock protein (HSP) 70 and HSP90 molecular chaperone networks have been associated with neurodegenerative diseases caused by aberrant protein-folding. The pathogenesis of these disorders usually includes the formation of deposits of misfolded, aggregated protein. HSP70 and HSP90, plus their co-chaperones, have been recognised as potent modulators of misfolded protein toxicity, inclusion formation and cell survival in cellular and animal models of neurodegenerative disease. Moreover, these chaperone machines function not only in folding but also in proteasome-mediated degradation of neurodegenerative disease proteins. This chapter gives an overview of the HSP70 and HSP90 chaperones, and their respective regulatory co-chaperones, and explores how the HSP70 and HSP90 chaperone systems form a larger functional network and its relevance to counteracting neurodegenerative disease associated with misfolded proteins and disruption of proteostasis.
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Affiliation(s)
| | - Xavi Aran-Guiu
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Jasmeen Oberoi
- Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Brighton, UK
| | - Laura Perna
- Centre for Endocrinology, William Harvey Research Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, London, UK
| | - J Paul Chapple
- Centre for Endocrinology, William Harvey Research Institute, Faculty of Medicine and Dentistry, Queen Mary University of London, London, UK.
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7
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Leung A, Sacristan-Reviriego A, Perdigão PRL, Sai H, Georgiou M, Kalitzeos A, Carr AJF, Coffey PJ, Michaelides M, Bainbridge J, Cheetham ME, van der Spuy J. Investigation of PTC124-mediated translational readthrough in a retinal organoid model of AIPL1-associated Leber congenital amaurosis. Stem Cell Reports 2022; 17:2187-2202. [PMID: 36084639 PMCID: PMC9561542 DOI: 10.1016/j.stemcr.2022.08.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 10/26/2022] Open
Abstract
Leber congenital amaurosis type 4 (LCA4), caused by AIPL1 mutations, is characterized by severe sight impairment in infancy and rapidly progressing degeneration of photoreceptor cells. We generated retinal organoids using induced pluripotent stem cells (iPSCs) from renal epithelial cells obtained from four children with AIPL1 nonsense mutations. iPSC-derived photoreceptors exhibited the molecular hallmarks of LCA4, including undetectable AIPL1 and rod cyclic guanosine monophosphate (cGMP) phosphodiesterase (PDE6) compared with control or CRISPR-corrected organoids. Increased levels of cGMP were detected. The translational readthrough-inducing drug (TRID) PTC124 was investigated as a potential therapeutic agent. LCA4 retinal organoids exhibited low levels of rescue of full-length AIPL1. However, this was insufficient to fully restore PDE6 in photoreceptors and reduce cGMP. LCA4 retinal organoids are a valuable platform for in vitro investigation of novel therapeutic agents.
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Affiliation(s)
- Amy Leung
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | | | | | - Hali Sai
- UCL Institute of Ophthalmology, London EC1V 9EL, UK
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - Angelos Kalitzeos
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | | | | | - Michel Michaelides
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
| | - James Bainbridge
- UCL Institute of Ophthalmology, London EC1V 9EL, UK; Moorfields Eye Hospital NHS Foundation Trust, London EC1V 2PD, UK
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8
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Ziaka K, van der Spuy J. The Role of Hsp90 in Retinal Proteostasis and Disease. Biomolecules 2022; 12:biom12070978. [PMID: 35883534 PMCID: PMC9313453 DOI: 10.3390/biom12070978] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/07/2022] [Accepted: 07/08/2022] [Indexed: 11/24/2022] Open
Abstract
Photoreceptors are sensitive neuronal cells with great metabolic demands, as they are responsible for carrying out visual phototransduction, a complex and multistep process that requires the exquisite coordination of a large number of signalling protein components. Therefore, the viability of photoreceptors relies on mechanisms that ensure a well-balanced and functional proteome that maintains the protein homeostasis, or proteostasis, of the cell. This review explores how the different isoforms of Hsp90, including the cytosolic Hsp90α/β, the mitochondrial TRAP1, and the ER-specific GRP94, are involved in the different proteostatic mechanisms of photoreceptors, and elaborates on Hsp90 function when retinal homeostasis is disturbed. In addition, several studies have shown that chemical manipulation of Hsp90 has significant consequences, both in healthy and degenerating retinae, and this can be partially attributed to the fact that Hsp90 interacts with important photoreceptor-associated client proteins. Here, the interaction of Hsp90 with the retina-specific client proteins PDE6 and GRK1 will be further discussed, providing additional insights for the role of Hsp90 in retinal disease.
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9
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Yadav RP, Boyd K, Artemyev NO. Molecular insights into the maturation of phosphodiesterase 6 by the specialized chaperone complex of HSP90 with AIPL1. J Biol Chem 2022; 298:101620. [PMID: 35065964 PMCID: PMC8857470 DOI: 10.1016/j.jbc.2022.101620] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Revised: 01/10/2022] [Accepted: 01/11/2022] [Indexed: 12/18/2022] Open
Abstract
Phosphodiesterase 6 (PDE6) is a key effector enzyme in vertebrate phototransduction, and its maturation and function are known to critically depend on a specialized chaperone, aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1). Defects in PDE6 and AIPL1 underlie several severe retinal diseases, including retinitis pigmentosa and Leber congenital amaurosis. Here, we characterize the complex of AIPL1 with HSP90 and demonstrate its essential role in promoting the functional conformation of nascent PDE6. Our analysis suggests that AIPL1 preferentially binds to HSP90 in the closed state with a stoichiometry of 1:2, with the tetratricopeptide repeat domain and the tetratricopeptide repeat helix 7 extension of AIPL1 being the main contributors to the AIPL1/HSP90 interface. We demonstrate that mutations of these determinants markedly diminished both the affinity of AIPL1 for HSP90 and the ability of AIPL1 to cochaperone the maturation of PDE6 in a heterologous expression system. In addition, the FK506-binding protein (FKBP) domain of AIPL1 encloses a unique prenyl-binding site that anchors AIPL1 to posttranslational lipid modifications of PDE6. A mouse model with rod PDE6 lacking farnesylation of its PDE6A subunit revealed normal expression, trafficking, and signaling of the enzyme. Furthermore, AIPL1 was unexpectedly capable of inducing the maturation of unprenylated cone PDE6C, whereas mutant AIPL1 deficient in prenyl binding competently cochaperoned prenylated PDE6C. Thus, we conclude neither sequestration of the prenyl modifications is required for PDE6 maturation to proceed, nor is the FKBP-lipid interaction involved in the conformational switch of the enzyme into the functional state.
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Affiliation(s)
- Ravi P Yadav
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Kimberly Boyd
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Nikolai O Artemyev
- Department of Molecular Physiology and Biophysics, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA; Department of Ophthalmology and Visual Sciences, The University of Iowa Carver College of Medicine, Iowa City, Iowa, USA.
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10
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Gulati S, Palczewski K. New focus on regulation of the rod photoreceptor phosphodiesterase. Curr Opin Struct Biol 2021; 69:99-107. [PMID: 33945959 DOI: 10.1016/j.sbi.2021.03.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 02/18/2021] [Accepted: 03/25/2021] [Indexed: 02/03/2023]
Abstract
Rod photoreceptor phosphodiesterase (PDE6) is the key catalytic enzyme of visual phototransduction. PDE6 is the only member of the phosphodiesterase family that consists of a heterodimeric catalytic core composed of PDE6α and PDE6β subunits and two inhibitory PDE6γ subunits. Both PDE6α and PDE6β contain two regulatory GAF domains and one catalytic domain. GAF domains and the tightly bound PDE6γ subunits allosterically regulate the activity of the catalytic domain in association with the GTP-bound transducin alpha subunit (Gtα-GTP). Recent cryo-electron microscopy structures of the PDE6αγβγ and PDE6αγβγ-(Gtα-GTP)2 complexes have provided valuable knowledge shedding additional light on the allosteric activation of PDE6 by Gtα-GTP. Here we discuss recent developments in our understanding of the mechanism of PDE6 activation.
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Affiliation(s)
| | - Krzysztof Palczewski
- Gavin Herbert Eye Institute and the Department of Ophthalmology, Center for Translational Vision Research, University of California, 829 Health Sciences Road, Irvine, CA 92617, USA; The Department of Physiology & Biophysics, University of California, Irvine, CA 92697, USA; The Department of Chemistry, University of California, Irvine, CA 92697, USA.
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11
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Sacristan-Reviriego A, Le HM, Georgiou M, Meunier I, Bocquet B, Roux AF, Prodromou C, Bainbridge J, Michaelides M, van der Spuy J. Clinical and functional analyses of AIPL1 variants reveal mechanisms of pathogenicity linked to different forms of retinal degeneration. Sci Rep 2020; 10:17520. [PMID: 33067476 PMCID: PMC7567831 DOI: 10.1038/s41598-020-74516-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 08/21/2020] [Indexed: 12/18/2022] Open
Abstract
Disease-causing sequence variants in the highly polymorphic AIPL1 gene are associated with a broad spectrum of inherited retinal diseases ranging from severe autosomal recessive Leber congenital amaurosis to later onset retinitis pigmentosa. AIPL1 is a photoreceptor-specific co-chaperone that interacts with HSP90 to facilitate the stable assembly of retinal cGMP phosphodiesterase, PDE6. In this report, we establish unequivocal correlations between patient clinical phenotypes and in vitro functional assays of uncharacterized AIPL1 variants. We confirm that missense and nonsense variants in the FKBP-like and tetratricopeptide repeat domains of AIPL1 lead to the loss of both HSP90 interaction and PDE6 activity, confirming these variants cause LCA. In contrast, we report the association of p.G122R with milder forms of retinal degeneration, and show that while p.G122R had no effect on HSP90 binding, the modulation of PDE6 cGMP levels was impaired. The clinical history of these patients together with our functional assays suggest that the p.G122R variant is a rare hypomorphic allele with a later disease onset, amenable to therapeutic intervention. Finally, we report the primate-specific proline-rich domain to be dispensable for both HSP90 interaction and PDE6 activity. We conclude that variants investigated in this domain do not cause disease, with the exception of p.A352_P355del associated with autosomal dominant cone-rod dystrophy.
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Affiliation(s)
| | - Hoang Mai Le
- UCL Institute of Ophthalmology, University College London, 11 - 43 Bath Street, London, EC1V 9EL, UK
| | - Michalis Georgiou
- UCL Institute of Ophthalmology, University College London, 11 - 43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, City Road, London, EC1V 2PD, UK
| | - Isabelle Meunier
- Centre National de Référence Maladies Sensorielles Génétiques, Service Ophtalmologie Hôpital Gui de Chauliac - CHRU de Montpellier, 80 rue Augustin Fliche, 34295, Montpellier, France
| | - Beatrice Bocquet
- Centre National de Référence Maladies Sensorielles Génétiques, Service Ophtalmologie Hôpital Gui de Chauliac - CHRU de Montpellier, 80 rue Augustin Fliche, 34295, Montpellier, France
| | - Anne-Françoise Roux
- Laboratoire de Génétique Moléculaire, CHU de Montpellier, Université de Montpellier, Montpellier, France
| | | | - James Bainbridge
- UCL Institute of Ophthalmology, University College London, 11 - 43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, City Road, London, EC1V 2PD, UK
| | - Michel Michaelides
- UCL Institute of Ophthalmology, University College London, 11 - 43 Bath Street, London, EC1V 9EL, UK.,Moorfields Eye Hospital, City Road, London, EC1V 2PD, UK
| | - Jacqueline van der Spuy
- UCL Institute of Ophthalmology, University College London, 11 - 43 Bath Street, London, EC1V 9EL, UK.
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12
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Boehm AN, Bialas J, Catone N, Sacristan-Reviriego A, van der Spuy J, Groettrup M, Aichem A. The ubiquitin-like modifier FAT10 inhibits retinal PDE6 activity and mediates its proteasomal degradation. J Biol Chem 2020; 295:14402-14418. [PMID: 32817338 DOI: 10.1074/jbc.ra120.013873] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Revised: 08/12/2020] [Indexed: 11/06/2022] Open
Abstract
The retina-specific chaperone aryl hydrocarbon interacting protein-like 1 (AIPL1) is essential for the correct assembly of phosphodiesterase 6 (PDE6), which is a pivotal effector enzyme for phototransduction and vision because it hydrolyzes cGMP. AIPL1 interacts with the cytokine-inducible ubiquitin-like modifier FAT10, which gets covalently conjugated to hundreds of proteins and targets its conjugation substrates for proteasomal degradation, but whether FAT10 affects PDE6 function or turnover is unknown. Here, we show that FAT10 mRNA is expressed in human retina and identify rod PDE6 as a retina-specific substrate of FAT10 conjugation. We found that AIPL1 stabilizes the FAT10 monomer and the PDE6-FAT10 conjugate. Additionally, we elucidated the functional consequences of PDE6 FAT10ylation. On the one hand, we demonstrate that FAT10 targets PDE6 for proteasomal degradation by formation of a covalent isopeptide linkage. On the other hand, FAT10 inhibits PDE6 cGMP hydrolyzing activity by noncovalently interacting with the PDE6 GAFa and catalytic domains. Therefore, FAT10 may contribute to loss of PDE6 and, as a consequence, degeneration of retinal cells in eye diseases linked to inflammation and inherited blindness-causing mutations in AIPL1.
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Affiliation(s)
- Annika N Boehm
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany.,Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | - Johanna Bialas
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany.,Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | - Nicola Catone
- Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | | | | | - Marcus Groettrup
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany.,Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
| | - Annette Aichem
- Division of Immunology, Department of Biology, University of Konstanz, Konstanz, Germany .,Biotechnology Institute Thurgau at the University of Konstanz, Kreuzlingen, Switzerland
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13
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Retinal Organoids derived from hiPSCs of an AIPL1-LCA Patient Maintain Cytoarchitecture despite Reduced levels of Mutant AIPL1. Sci Rep 2020; 10:5426. [PMID: 32214115 PMCID: PMC7096529 DOI: 10.1038/s41598-020-62047-2] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/02/2020] [Indexed: 12/22/2022] Open
Abstract
Aryl hydrocarbon receptor-interacting protein-like 1 (AIPL1) is a photoreceptor-specific chaperone that stabilizes the effector enzyme of phototransduction, cGMP phosphodiesterase 6 (PDE6). Mutations in the AIPL1 gene cause a severe inherited retinal dystrophy, Leber congenital amaurosis type 4 (LCA4), that manifests as the loss of vision during the first year of life. In this study, we generated three-dimensional (3D) retinal organoids (ROs) from human induced pluripotent stem cells (hiPSCs) derived from an LCA4 patient carrying a Cys89Arg mutation in AIPL1. This study aimed to (i) explore whether the patient hiPSC-derived ROs recapitulate LCA4 disease phenotype, and (ii) generate a clinically relevant resource to investigate the molecular mechanism of disease and safely test novel therapies for LCA4 in vitro. We demonstrate reduced levels of the mutant AIPL1 and PDE6 proteins in patient organoids, corroborating the findings in animal models; however, patient-derived organoids maintained retinal cell cytoarchitecture despite significantly reduced levels of AIPL1.
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14
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Moreno-Morcillo M, Francisco-Velilla R, Embarc-Buh A, Fernández-Chamorro J, Ramón-Maiques S, Martinez-Salas E. Structural basis for the dimerization of Gemin5 and its role in protein recruitment and translation control. Nucleic Acids Res 2020; 48:788-801. [PMID: 31799608 PMCID: PMC6954437 DOI: 10.1093/nar/gkz1126] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/12/2019] [Accepted: 11/18/2019] [Indexed: 12/21/2022] Open
Abstract
In all organisms, a selected type of proteins accomplishes critical roles in cellular processes that govern gene expression. The multifunctional protein Gemin5 cooperates in translation control and ribosome binding, besides acting as the RNA-binding protein of the survival of motor neuron (SMN) complex. While these functions reside on distinct domains located at each end of the protein, the structure and function of the middle region remained unknown. Here, we solved the crystal structure of an extended tetratricopeptide (TPR)-like domain in human Gemin5 that self-assembles into a previously unknown canoe-shaped dimer. We further show that the dimerization module is functional in living cells driving the interaction between the viral-induced cleavage fragment p85 and the full-length Gemin5, which anchors splicing and translation members. Disruption of the dimerization surface by a point mutation in the TPR-like domain prevents this interaction and also abrogates translation enhancement induced by p85. The characterization of this unanticipated dimerization domain provides the structural basis for a role of the middle region of Gemin5 as a central hub for protein-protein interactions.
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Affiliation(s)
- María Moreno-Morcillo
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain
| | | | - Azman Embarc-Buh
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain
| | | | - Santiago Ramón-Maiques
- Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Nicolás Cabrera 1, 28049 Madrid, Spain.,Group 739, Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER)- Instituto de Salud Carlos III, Valencia, Spain
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15
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Kolos JM, Voll AM, Bauder M, Hausch F. FKBP Ligands-Where We Are and Where to Go? Front Pharmacol 2018; 9:1425. [PMID: 30568592 PMCID: PMC6290070 DOI: 10.3389/fphar.2018.01425] [Citation(s) in RCA: 97] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Accepted: 11/19/2018] [Indexed: 12/24/2022] Open
Abstract
In recent years, many members of the FK506-binding protein (FKBP) family were increasingly linked to various diseases. The binding domain of FKBPs differs only in a few amino acid residues, but their biological roles are versatile. High-affinity ligands with selectivity between close homologs are scarce. This review will give an overview of the most prominent ligands developed for FKBPs and highlight a perspective for future developments. More precisely, human FKBPs and correlated diseases will be discussed as well as microbial FKBPs in the context of anti-bacterial and anti-fungal therapeutics. The last section gives insights into high-affinity ligands as chemical tools and dimerizers.
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Affiliation(s)
| | | | | | - Felix Hausch
- Department of Chemistry, Institute of Chemistry and Biochemistry, Darmstadt University of Technology, Darmstadt, Germany
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