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Ando R, Noda K, Tomaru U, Kamoshita M, Ozawa Y, Notomi S, Hisatomi T, Noda M, Kanda A, Ishibashi T, Kasahara M, Ishida S. Decreased proteasomal activity causes photoreceptor degeneration in mice. Invest Ophthalmol Vis Sci 2014; 55:4682-90. [PMID: 24994871 DOI: 10.1167/iovs.13-13272] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
PURPOSE To study the retinal degeneration caused by decreased proteasomal activity in β5t transgenic (β5t-Tg) mice, an animal model of senescence acceleration. METHODS β5t-Tg mice and age-matched littermate control (WT) mice were used. Proteasomal activities and protein level of poly-ubiquitinated protein in retinal extracts were quantified. Fundus images of β5t-Tg mice were taken and their features were assessed. For histologic evaluation, the thicknesses of inner nuclear layer (INL), outer nuclear layer (ONL), and photoreceptor outer segment (OS) were measured. For functional analysis, ERG was recorded under scotopic and photopic illumination conditions. Immunofluorescence (IF) staining and TUNEL were performed to investigate the mechanism of photoreceptor degeneration. RESULTS Chymotrypsin-like activity was partially suppressed in retinal tissues of β5t-Tg mice. Retinal degenerative changes with arterial attenuation were present in β5t-Tg, but not in WT mice. Inner nuclear layer thickness showed no significant change between β5t-Tg and WT mice at 1, 3, 6, and 9 months of age. By contrast, thicknesses of ONL and OS in β5t-Tg mice were significantly decreased at 3, 6, and 9 months compared with those in WT mice. Electroretinograms showed decrease of scotopic a-wave amplitude in β5t-Tg mice. The number of TUNEL-positive cells in ONL were significantly increased in β5t-Tg mice and colocalized with apoptosis-inducing factor, but not with cleaved caspase-3 and -9, indicating that the photoreceptor cell death was induced via a caspase-independent pathway. CONCLUSIONS The current data showed that impaired proteasomal function causes photoreceptor degeneration.
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Affiliation(s)
- Ryo Ando
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Kousuke Noda
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Utano Tomaru
- Department of Pathology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Mamoru Kamoshita
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Yoko Ozawa
- Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | - Shoji Notomi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Toshio Hisatomi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Mika Noda
- Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Atsuhiro Kanda
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Tatsuro Ishibashi
- Department of Ophthalmology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Masanori Kasahara
- Department of Pathology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
| | - Susumu Ishida
- Laboratory of Ocular Cell Biology & Visual Science, Hokkaido University Graduate School of Medicine, Sapporo, Japan Department of Ophthalmology, Hokkaido University Graduate School of Medicine, Sapporo, Japan
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