Pharmacological clearance of misfolded rhodopsin for the treatment of RHO-associated retinitis pigmentosa.

Abstract

Rhodopsin mutation and misfolding is a common cause of autosomal dominant retinitis pigmentosa (RP). Using a luciferase reporter assay, we undertook a small-molecule high-throughput screening (HTS) of 68, 979 compounds and identified nine compounds that selectively reduced the misfolded P23H rhodopsin without an effect on the wild type (WT) rhodopsin protein. Further, we found five of these compounds, including methotrexate (MTX), promoted P23H rhodopsin degradation that also cleared out other misfolded rhodopsin mutant proteins. We showed MTX increased P23H rhodopsin degradation via the lysosomal but not the proteasomal pathway. Importantly, one intravitreal injection (IVI) of 25 pmol MTX increased electroretinogram (ERG) response and rhodopsin level in the retinae of RhoP23H/+ knock-in mice at 1 month of age. Additionally, four weekly IVIs increased the photoreceptor cell number in the retinae of RhoP23H/+ mice compared to vehicle control. Our study indicates a therapeutic potential of repurposing MTX for the treatment of rhodopsin-associated RP.

• Authors: Xujie Liu, Bing Feng, Abhishek Vats, Hong Tang, William Seibel, Manju Swaroop, Gregory Tawa, Wei Zheng, Leah Byrne, Mark Schurdak, Yuanyuan Chen
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 34 Issue 8 Pg. 10146-10167 (08 2020) ISSN: 1530-6860 [Electronic] United States
• PMID: 32536017 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
• Copyright: © 2020 The Authors. The FASEB Journal published by Wiley Periodicals LLC on behalf of Federation of American Societies for Experimental Biology.

Chemical References

• Mutant Proteins
• Rhodopsin
• Proteasome Endopeptidase Complex

Topics

• Animals
• Cell Line
• Electroretinography (methods)
• Female
• HEK293 Cells
• Humans
• Male
• Mice
• Mutant Proteins (metabolism)
• Mutation (genetics)
• NIH 3T3 Cells
• Photoreceptor Cells (metabolism)
• Proteasome Endopeptidase Complex (metabolism)
• Protein Folding
• Retina (metabolism)
• Retinitis Pigmentosa (genetics, metabolism)
• Rhodopsin (genetics, metabolism)