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Alice N. Hackett, Rivka Rachel, Lijin Dong, Anand Swaroop; Unique Functions of CEP290 Domains in Retinal Degeneration. Invest. Ophthalmol. Vis. Sci. 2011;52(14):2365.
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© ARVO (1962-2015); The Authors (2016-present)
Mutations in centrosomal/ciliary protein CEP290 cause a broad spectrum of phenotypes resulting in ciliopathies, including Leber congenital amaurosis. The goal of this project is to elucidate disease pathogenesis and design treatment paradigms by characterizing retinal degeneration phenotypes of mice with three distinct Cep290 alleles: knockout (null), genetrap (C-term truncation), and rd16 (ΔDSD).
Knockout mice were generated by replacing exons 1-4 of the Cep290 gene with a lacZ neo cassette, resulting in a null allele. Genetrap mice have a 3’-truncated allele of Cep290 in which a lacZ genetrap cassette inserted in intron 25. Cep290rd16 mice have a spontaneous in-frame deletion of exons 35-39 resulting in removal of the DSD domain. Development and degeneration of the retina were evaluated by histology and immunohistochemistry in all three lines, including compound heterozygotes.
Compared to WT mice, at P16 Cep290 knockout mice (KoKo) have a thinner outer nuclear layer (ONL), shorter inner and outer segments (IS and OS), and abnormal morphology, with loss of the ONL by P21. Genetrap and rd16 mutations show less severe IS and OS defects and slightly slower degeneration. The knockout - rd16 allelic combination (KoRd) has a thin ONL with apoptotic cells and abnormal structure of the IS and OS. The knockout -genetrap combination (KoGt) shows a thinner ONL than the KoRd combination, lacks OS, and has abnormal, short IS. The genetrap - rd16 phenotype (GtRd) is less severe than the KoRd or KoGt combinations. The severity of ONL degeneration of these allele combinations, starting from the most severe, is KoKo, KoGt, KoRd, GtRd, and then RdRd mice.
KoKo mice exhibit the most rapid retinal degeneration, and KoGt mice have a more severe phenotype than KoRd mice. Interestingly, KoKo mice retain IS and OS- although they are abnormal, yet in KoGt mice OS are completely gone. A complete characterization of retinal degeneration caused by these mutations will be useful in understanding underlying mechanisms and function of the CEP290 protein. Our studies should lead to better design of treatments for CEP290 mutations in Leber congenital amaurosis and other ciliopathies.
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