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Kretschmer V, Schneider S, Matthiessen PA, Reichert D, Hotaling N, Glasßer G, Lieberwirth I, Bharti K, De Cegli R, Conte I, Nandrot EF, May-Simera HL. Deletion of IFT20 exclusively in the RPE ablates primary cilia and leads to retinal degeneration. PLoS Biol 2023; 21:e3002402. [PMID: 38048369 PMCID: PMC10721183 DOI: 10.1371/journal.pbio.3002402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 12/14/2023] [Accepted: 10/26/2023] [Indexed: 12/06/2023] Open
Abstract
Vision impairment places a serious burden on the aging society, affecting the lives of millions of people. Many retinal diseases are of genetic origin, of which over 50% are due to mutations in cilia-associated genes. Most research on retinal degeneration has focused on the ciliated photoreceptor cells of the retina. However, the contribution of primary cilia in other ocular cell types has largely been ignored. The retinal pigment epithelium (RPE) is a monolayer epithelium at the back of the eye intricately associated with photoreceptors and essential for visual function. It is already known that primary cilia in the RPE are critical for its development and maturation; however, it remains unclear whether this affects RPE function and retinal tissue homeostasis. We generated a conditional knockout mouse model, in which IFT20 is exclusively deleted in the RPE, ablating primary cilia. This leads to defective RPE function, followed by photoreceptor degeneration and, ultimately, vision impairment. Transcriptomic analysis offers insights into mechanisms underlying pathogenic changes, which include transcripts related to epithelial homeostasis, the visual cycle, and phagocytosis. Due to the loss of cilia exclusively in the RPE, this mouse model enables us to tease out the functional role of RPE cilia and their contribution to retinal degeneration, providing a powerful tool for basic and translational research in syndromic and non-syndromic retinal degeneration. Non-ciliary mechanisms of IFT20 in the RPE may also contribute to pathogenesis and cannot be excluded, especially considering the increasing evidence of non-ciliary functions of ciliary proteins.
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Affiliation(s)
- Viola Kretschmer
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Sandra Schneider
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Peter Andreas Matthiessen
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
| | - Dominik Reichert
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Nathan Hotaling
- National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Gunnar Glasßer
- Max Planck Institute for Polymer Research, Mainz, Germany
| | | | - Kapil Bharti
- National Eye Institute, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Rossella De Cegli
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
| | - Ivan Conte
- Telethon Institute of Genetics and Medicine (TIGEM), Pozzuoli, Italy
- University of Naples “Federico II”, Naples, Italy
| | | | - Helen Louise May-Simera
- Faculty of Biology, Institute of Molecular Physiology, Johannes Gutenberg-University, Mainz, Germany
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Nguyen MN, Chakraborty D, Rao SR, Onysk A, Radkiewicz M, Surmacz L, Swiezewska E, Soubeyrand E, Akhtar TA, Kraft TW, Sherry DM, Fliesler SJ, Pittler SJ. A Dhdds K42E knock-in RP59 mouse model shows inner retina pathology and defective synaptic transmission. Cell Death Dis 2023; 14:420. [PMID: 37443173 PMCID: PMC10345138 DOI: 10.1038/s41419-023-05936-4] [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: 09/11/2022] [Revised: 06/07/2023] [Accepted: 06/29/2023] [Indexed: 07/15/2023]
Abstract
Retinitis pigmentosa (RP) defines a group of hereditary progressive rod-cone degenerations that exhibit a common phenotype caused by variants in over 70 genes. While most variants in the dehydrodolichyl diphosphate synthase (DHDDS) gene result in syndromic abnormalities, some variants cause non-syndromic RP (RP59). DHDDS encodes one subunit of the enzyme cis-prenyltransferase (CPT), which is required for the synthesis of dolichol (Dol), that is a necessary protein glycosylation cofactor. We previously reported the creation and initial characterization of a knock-in (KI) mouse model harboring the most prevalent RP59-associated DHDDS variant (K42E) to understand how defects in DHDDS lead to retina-specific pathology. This model exhibited no profound retinal degeneration, nor protein N-glycosylation defects. Here, we report that the Dol isoprenylogue species in retina, liver, and brain of the K42E mouse model are statistically shorter than in the corresponding tissues of age-matched controls, as reported in blood and urine of RP59 patients. Retinal transcriptome analysis demonstrated elevation of many genes encoding proteins involved in synaptogenesis and synaptic function. Quantitative retinal cell layer thickness measurements demonstrated a significant reduction in the inner nuclear layer (INL) and total retinal thickness (TRT) beginning at postnatal (PN) ∼2 months, progressively increasing to PN 18-mo. Histological analysis revealed cell loss in the INL, outer plexiform layer (OPL) disruption, and ectopic localization of outer nuclear layer (ONL) nuclei into the OPL of K42E mutant retinas, relative to controls. Electroretinograms (ERGs) of mutant mice exhibited reduced b-wave amplitudes beginning at PN 1-mo, progressively declining through PN 18-mo, without appreciable a-wave attenuation, relative to controls. Our results suggest that the underlying cause of DHDDS K42E variant driven RP59 retinal pathology is defective synaptic transmission from outer to inner retina.
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Affiliation(s)
- Mai N Nguyen
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Dibyendu Chakraborty
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Sriganesh Ramachandra Rao
- Research Service, VA Western New York Healthcare System, Buffalo, NY, 14215, USA
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, 14203, USA
| | - Agnieszka Onysk
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02106, Poland
| | - Mariusz Radkiewicz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02106, Poland
| | - Liliana Surmacz
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02106, Poland
| | - Ewa Swiezewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02106, Poland
| | - Eric Soubeyrand
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G2W1, Canada
| | - Tariq A Akhtar
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G2W1, Canada
| | - Timothy W Kraft
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - David M Sherry
- Departments of Cell Biology, Neurosurgery, and Pharmaceutical Sciences, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA
| | - Steven J Fliesler
- Research Service, VA Western New York Healthcare System, Buffalo, NY, 14215, USA
- Departments of Ophthalmology and Biochemistry and Neuroscience Graduate Program, Jacobs School of Medicine and Biomedical Sciences, The State University of New York, University at Buffalo, Buffalo, NY, 14203, USA
| | - Steven J Pittler
- Department of Optometry and Vision Science, Vision Science Research Center, School of Optometry, University of Alabama at Birmingham, Birmingham, AL, 35294, USA.
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3
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Choi EH, Suh S, Einstein DE, Leinonen H, Dong Z, Rao SR, Fliesler SJ, Blackshaw S, Yu M, Peachey NS, Palczewski K, Kiser PD. An inducible Cre mouse for studying roles of the RPE in retinal physiology and disease. JCI Insight 2021; 6:146604. [PMID: 33784255 PMCID: PMC8262343 DOI: 10.1172/jci.insight.146604] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 03/25/2021] [Indexed: 01/04/2023] Open
Abstract
The retinal pigment epithelium (RPE) provides vital metabolic support for retinal photoreceptor cells and is an important player in numerous retinal diseases. Gene manipulation in mice using the Cre-LoxP system is an invaluable tool for studying the genetic basis of these retinal diseases. However, existing RPE-targeted Cre mouse lines have critical limitations that restrict their reliability for studies of disease pathogenesis and treatment, including mosaic Cre expression, inducer-independent activity, off-target Cre expression, and intrinsic toxicity. Here, we report the generation and characterization of a knockin mouse line in which a P2A-CreERT2 coding sequence is fused with the native RPE-specific 65 kDa protein (Rpe65) gene for cotranslational expression of CreERT2. Cre+/– mice were able to recombine a stringent Cre reporter allele with more than 99% efficiency and absolute RPE specificity upon tamoxifen induction at both postnatal days (PD) 21 and 50. Tamoxifen-independent Cre activity was negligible at PD64. Moreover, tamoxifen-treated Cre+/– mice displayed no signs of structural or functional retinal pathology up to 4 months of age. Despite weak RPE65 expression from the knockin allele, visual cycle function was normal in Cre+/– mice. These data indicate that Rpe65CreERT2 mice are well suited for studies of gene function and pathophysiology in the RPE.
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Affiliation(s)
- Elliot H Choi
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - Susie Suh
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio, USA
| | - David E Einstein
- Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
| | - Henri Leinonen
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - Zhiqian Dong
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA
| | - Sriganesh Ramachandra Rao
- Departments of Ophthalmology and Biochemistry, Jacobs School of Medicine and Biomedical Sciences and.,Neuroscience Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York, USA.,Research Service, VA Western New York Healthcare System, Buffalo, New York, USA
| | - Steven J Fliesler
- Departments of Ophthalmology and Biochemistry, Jacobs School of Medicine and Biomedical Sciences and.,Neuroscience Graduate Program, University at Buffalo, The State University of New York, Buffalo, New York, USA.,Research Service, VA Western New York Healthcare System, Buffalo, New York, USA
| | - Seth Blackshaw
- Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
| | - Minzhong Yu
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA
| | - Neal S Peachey
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic Foundation, Cleveland, Ohio, USA.,Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, Ohio, USA.,Research Service, Louis Stokes Cleveland VA Medical Center, Cleveland, Ohio, USA
| | - Krzysztof Palczewski
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Department of Chemistry, School of Physical Sciences, University of California, Irvine, Irvine, California, USA
| | - Philip D Kiser
- Department of Ophthalmology, Gavin Herbert Eye Institute, University of California, Irvine, Irvine, California, USA.,Department of Physiology and Biophysics, School of Medicine, University of California, Irvine, Irvine, California, USA.,Research Service, VA Long Beach Healthcare System, Long Beach, California, USA
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