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Erin Yamamoto, Rivka Rachel, Mrinal Dewanjee, Jeeva Munasinghe, Tiansen Li, Lijin Dong, Anand Swaroop; CEP290 is Required for Photoreceptor Ciliogenesis and Ventricular Ependymal Cilia Function. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6553.
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© ARVO (1962-2015); The Authors (2016-present)
Mutations in CEP290, which encodes a centrosomal/cilia protein, result in a range of human ciliopathies including Leber congenital amaurosis. The aim of this project is to understand Cep290 function by analyzing phenotypes of the Cep290-knockout (Cep290-/-) mouse.
We exchanged exons 1-4 of the Cep290 gene with a lacZ-neo cassette to generate the Cep290-/- mice. CEP290 was localized by confocal immunohistochemistry (IHC) and immunoEM. Retinal degeneration was evaluated by histology and IHC. The brain phenotype was analyzed through SEM, MRI, and IHC.
By both confocal and electron microscopy, CEP290 localizes to connecting cilia, adjacent to microtubules in wild-type (WT) photoreceptors, and to the ependymal cells lining the brain ventricles. We find impaired ciliogenesis in photoreceptors of Cep290-/- mice, though the basal bodies and associated microtubule assemblies are present. Cep290-/- mice have early retinal degeneration and most develop hydrocephalus between two and four weeks of age. The retinal degeneration in Cep290-/- mice is characterized by loss of photoreceptors and a substantial decrease in ONL thickness between P14 and P28. A vast majority (80-100%) of Cep290-/- mice do not survive past P21 due to worsening hydrocephalus, as visualized by high-resolution MRI. Compared to the tufts of cilia lining the WT ventricular epithelium, ependymal cells in the Cep290-/- mice have reduced numbers of unorganized cilia. We are examining whether the lack of cilia on the ventricular epithelium is the cause or a result of the hydrocephalus and increased intracranial pressure. The Cep290+/- mice appear normal and do not have retinal degeneration or hydrocephalus, demonstrating haplosufficiency.
The presence of basal bodies and microtubule rings without connecting cilia or outer segments in Cep290-/- photoreceptors imply that CEP290 is essential for ciliogenesis in photoreceptors. Our results also indicate that CEP290 plays a critical role in ciliogenesis and/or cilia function in subsets of neurons and have begun to shed light on underlying mechanisms in ciliopathies. Our studies of Cep290 interactions and function may unravel therapeutic approaches to ameliorate retinal degenerative diseases that involve cilia dysfunction.
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