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Yanardag S, Rhodes S, Saravanan T, Guan T, Ramamurthy V. Prominin 1 is crucial for the early development of photoreceptor outer segments. Sci Rep 2024; 14:10498. [PMID: 38714794 PMCID: PMC11076519 DOI: 10.1038/s41598-024-60989-5] [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: 03/12/2024] [Accepted: 04/30/2024] [Indexed: 05/10/2024] Open
Abstract
Prominin 1 (PROM1) is a pentaspan transmembrane glycoprotein localized on the nascent photoreceptor discs. Mutations in PROM1 are linked to various retinal diseases. In this study, we assessed the role of PROM1 in photoreceptor biology and physiology using the PROM1 knockout murine model (rd19). Our study found that PROM1 is essential for vision and photoreceptor development. We found an early reduction in photoreceptor response beginning at post-natal day 12 (P12) before eye opening in the absence of PROM1 with no apparent loss in photoreceptor cells. However, at this stage, we observed an increased glial cell activation, indicative of cell damage. Contrary to our expectations, dark rearing did not mitigate photoreceptor degeneration or vision loss in PROM1 knockout mice. In addition to physiological defects seen in PROM1 knockout mice, ultrastructural analysis revealed malformed outer segments characterized by whorl-like continuous membranes instead of stacked disks. In parallel to the reduced rod response at P12, proteomics revealed a significant reduction in the levels of protocadherin, a known interactor of PROM1, and rod photoreceptor outer segment proteins, including rhodopsin. Overall, our results underscore the indispensable role of PROM1 in photoreceptor development and maintenance of healthy vision.
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Affiliation(s)
- Sila Yanardag
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
| | - Scott Rhodes
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Thamaraiselvi Saravanan
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Tongju Guan
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA
| | - Visvanathan Ramamurthy
- Department of Biochemistry and Molecular Medicine, West Virginia University, Morgantown, WV, USA.
- Department of Ophthalmology and Visual Sciences, West Virginia University, Morgantown, WV, USA.
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Aljammal R, Saravanan T, Guan T, Rhodes S, Robichaux MA, Ramamurthy V. Excessive tubulin glutamylation leads to progressive cone-rod dystrophy and loss of outer segment integrity. Hum Mol Genet 2024; 33:802-817. [PMID: 38297980 DOI: 10.1093/hmg/ddae013] [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: 10/25/2023] [Revised: 12/29/2023] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
Mutations in Cytosolic Carboxypeptidase-like Protein 5 (CCP5) are associated with vision loss in humans. To decipher the mechanisms behind CCP5-associated blindness, we generated a novel mouse model lacking CCP5. In this model, we found that increased tubulin glutamylation led to progressive cone-rod dystrophy, with cones showing a more pronounced and earlier functional loss than rod photoreceptors. The observed functional reduction was not due to cell death, levels, or the mislocalization of major phototransduction proteins. Instead, the increased tubulin glutamylation caused shortened photoreceptor axonemes and the formation of numerous abnormal membranous whorls that disrupted the integrity of photoreceptor outer segments (OS). Ultimately, excessive tubulin glutamylation led to the progressive loss of photoreceptors, affecting cones more severely than rods. Our results highlight the importance of maintaining tubulin glutamylation for normal photoreceptor function. Furthermore, we demonstrate that murine cone photoreceptors are more sensitive to disrupted tubulin glutamylation levels than rods, suggesting an essential role for axoneme in the structural integrity of the cone outer segment. This study provides valuable insights into the mechanisms of photoreceptor diseases linked to excessive tubulin glutamylation.
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Affiliation(s)
- Rawaa Aljammal
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Thamaraiselvi Saravanan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Tongju Guan
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Scott Rhodes
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Michael A Robichaux
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
| | - Visvanathan Ramamurthy
- Department of Biochemistry and Molecular Medicine, School of Medicine, West Virginia University, 64 Medical Center Dr., Morgantown, WV 26506, United States
- Department of Ophthalmology and Visual Sciences, One Stadium Dr, West Virginia University, Morgantown, WV 26506, United States
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