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Ludwig J, Sawant OB, Wood J, Singamsetty S, Pan X, Bonilha VL, Rao S, Pshezhetsky AV. Histological characterization of retinal degeneration in mucopolysaccharidosis type IIIC. Exp Eye Res 2023; 229:109433. [PMID: 36858249 PMCID: PMC10103010 DOI: 10.1016/j.exer.2023.109433] [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: 11/14/2022] [Revised: 02/14/2023] [Accepted: 02/25/2023] [Indexed: 03/03/2023]
Abstract
Heparan-α-glucosaminide N-acetyltransferase (HGSNAT) participates in lysosomal degradation of heparan sulfate. Mutations in the gene encoding this enzyme cause mucopolysaccharidosis IIIC (MPS IIIC) or Sanfilippo syndrome type C. MPS IIIC patients exhibit progressive neurodegeneration, leading to dementia and death in early adulthood. Currently there is no approved treatment for MPS IIIC. Incidences of non-syndromic retinitis pigmentosa and early signs of night blindness are reported in some MPS IIIC patients, however the majority of ocular phenotypes are not well characterized. The goal of this study was to investigate retinal degeneration phenotype in the Hgsnat knockout mouse model of MPS IIIC and a cadaveric human MPS IIIC eye. Cone and rod photoreceptors in the eyes of homozygous 6-month-old Hgsnat knockout mice and their wild-type counterparts were analyzed using cone arrestin, S-opsin, M-opsin and rhodopsin antibodies. Histological observation was performed on the eye from a 35-year-old MPS IIIC donor. We observed a nearly 50% reduction in the rod photoreceptors density in the Hgsnat knockout mice compared to the littermate wild-type controls. Cone photoreceptor density was unaltered at this age. Severe retinal degeneration was also observed in the MPS IIIC donor eye. To our knowledge, this is the first report characterizing ocular phenotypes arising from deleterious variants in the Hgsnat gene associated with MPS IIIC clinical phenotype. Our findings indicate retinal manifestations may be present even before behavioral manifestations. Thus, we speculate that ophthalmological evaluations could be used as diagnostic indicators of early disease, progression, and end-point evaluation for future MPS IIIC therapies.
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Affiliation(s)
- Jessica Ludwig
- Center for Vision and Eye Banking Research, Eversight, Cleveland, OH, 44103, USA
| | - Onkar B Sawant
- Center for Vision and Eye Banking Research, Eversight, Cleveland, OH, 44103, USA.
| | | | | | - Xuefang Pan
- Sainte-Justine University Hospital Research Center, University of Montreal, Montreal, Quebec, Canada
| | - Vera L Bonilha
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Sujata Rao
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Alexey V Pshezhetsky
- Sainte-Justine University Hospital Research Center, University of Montreal, Montreal, Quebec, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada
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Jidigam VK, Sawant OB, Fuller RD, Wilcots K, Singh R, Lang RA, Rao S. Neuronal Bmal1 regulates retinal angiogenesis and neovascularization in mice. Commun Biol 2022; 5:792. [PMID: 35933488 PMCID: PMC9357084 DOI: 10.1038/s42003-022-03774-2] [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: 04/05/2022] [Accepted: 07/26/2022] [Indexed: 11/20/2022] Open
Abstract
Circadian clocks in the mammalian retina regulate a diverse range of retinal functions that allow the retina to adapt to the light-dark cycle. Emerging evidence suggests a link between the circadian clock and retinopathies though the causality has not been established. Here we report that clock genes are expressed in the mouse embryonic retina, and the embryonic retina requires light cues to maintain robust circadian expression of the core clock gene, Bmal1. Deletion of Bmal1 and Per2 from the retinal neurons results in retinal angiogenic defects similar to when animals are maintained under constant light conditions. Using two different models to assess pathological neovascularization, we show that neuronal Bmal1 deletion reduces neovascularization with reduced vascular leakage, suggesting that a dysregulated circadian clock primarily drives neovascularization. Chromatin immunoprecipitation sequencing analysis suggests that semaphorin signaling is the dominant pathway regulated by Bmal1. Our data indicate that therapeutic silencing of the retinal clock could be a common approach for the treatment of certain retinopathies like diabetic retinopathy and retinopathy of prematurity.
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Affiliation(s)
- Vijay K Jidigam
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Onkar B Sawant
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
- Eversight, Cleveland, OH, 44103, USA
| | - Rebecca D Fuller
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Kenya Wilcots
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
- Department of Chemistry, Cleveland State University, Cleveland, OH, 44115, USA
| | - Rupesh Singh
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA
| | - Richard A Lang
- Division of Developmental Biology, Cincinnati Children's Hospital, Cincinnati, OH, USA
- Department of Ophthalmology, College of Medicine, University of Cincinnati, Cincinnati, OH, USA
| | - Sujata Rao
- Department of Ophthalmic Research, Cole Eye Institute, Cleveland Clinic, Cleveland, OH, 44195, USA.
- Department of Ophthalmology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Cleveland, OH, 44195, USA.
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