UMMS Affiliation

Department of Ophthalmology and Visual Sciences

Publication Date


Document Type



Amino Acids, Peptides, and Proteins | Congenital, Hereditary, and Neonatal Diseases and Abnormalities | Eye Diseases | Genetic Phenomena | Genetics and Genomics


X-linked retinitis pigmentosa 2 (XLRP2) patients and Rp2 (null) mice exhibit severe cone photoreceptor degeneration. However, due to the paucity of cones in mammalian model systems, it is not clear how cones respond to the loss of RP2. Here we have used the Nrl(-/-) mice, which develop a rodless and short wavelength (S) opsin-containing cone-only retina, to generate Rp2 (null)::Nrl(-/-) double knock out (Rp2-DKO) mice. We found that the ciliary axoneme and the outer segments (OSs) of the cones were significantly longer with disorganized membrane infoldings as compared to the Nrl(-/-) mice. Additionally, we found misregulation in the expression of the genes related to ophthalmic disease, cell trafficking, and stress-response in the Rp2-DKO mice prior to the onset of cone degeneration. Surprisingly, the loss of RP2 did not affect progressive photoreceptor dysfunction of the Nrl(-/-) mice and the trafficking of S opsin. Our data suggest that RP2 is a negative regulator of cone OS length but does not affect S-opsin trafficking and S-cone function. Our studies also provide a cone-only platform to design cone-targeted therapeutic strategies for X-linked RP2.


cilia, ciliopathies, cone, opsin, photoreceptors, retinal degeneration

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Copyright © 2019 Li, Rao and Khanna. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

DOI of Published Version



Front Genet. 2019 Apr 5;10:323. doi: 10.3389/fgene.2019.00323. eCollection 2019. Link to article on publisher's site

Journal/Book/Conference Title

Frontiers in genetics

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Link to Article in PubMed

PubMed ID


Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.