Insights into the mechanisms of macular degeneration associated with the R172W mutation in RDS.
Mutations in the photoreceptor tetraspanin gene peripherin-2/retinal degeneration slow (PRPH2/RDS) cause both rod- and cone-dominant diseases. While rod-dominant diseases, such as autosomal dominant retinitis pigmentosa, are thought to arise due to haploinsufficiency caused by loss-of-function mutations, the mechanisms underlying PRPH2-associated cone-dominant diseases are unclear. Here we took advantage of a transgenic mouse line expressing an RDS mutant (R172W) known to cause macular degeneration (MD) in humans. To facilitate the study of cones in the heavily rod-dominant mouse retina, R172W mice were bred onto an Nrl(-/-) background (in which developing rods adopt a cone-like fate). In this model the R172W protein and the key RDS-binding partner, rod outer segment (OS) membrane protein 1 (ROM-1), were properly expressed and trafficked to cone OSs. However, the expression of R172W led to dominant defects in cone structure and function with equal effects on S- and M-cones. Furthermore, the expression of R172W in cones induced subtle alterations in RDS/ROM-1 complex assembly, specifically resulting in the formation of abnormal, large molecular weight ROM-1 complexes. Fundus imaging demonstrated that R172W mice developed severe clinical signs of disease nearly identical to those seen in human MD patients, including retinal degeneration, retinal pigment epithlium (RPE) defects and loss of the choriocapillaris. Collectively, these data identify a primary disease-causing molecular defect in cone cells and suggest that RDS-associated disease in patients may be a result of this defect coupled with secondary sequellae involving RPE and choriocapillaris cell loss.
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA.
Shannon M
SM
Conley
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA.
Michael W
MW
Stuck
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA.
Justin L
JL
Burnett
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA.
Dibyendu
D
Chakraborty
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA.
Seifollah
S
Azadi
Research Service, Veterans Administration Western New York Healthcare System, Buffalo, NY 14215, USA Departments of Ophthalmology (Ross Eye Institute) and Biochemistry, University at Buffalo-S.U.N.Y, Buffalo, NY 14215, USA.
Steven J
SJ
Fliesler
Department of Cell Biology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Boulevard, BMSB 781, Oklahoma City, OK 73104, USA muna-naash@ouhsc.edu.
Muna I
MI
Naash
D019943:Amino Acid Substitution; D000818:Animals; D001120:Arginine / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000235:genetics; D004195:Disease Models, Animal; D005136:Eye Proteins / Q000235:genetics / Q000378:metabolism*; D005654:Fundus Oculi; D006801:Humans; D008268:Macular Degeneration / Q000235:genetics / Q000473:pathology*; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D008822:Mice, Transgenic; D064531:Peripherins / Q000235:genetics* / Q000378:metabolism*; D017949:Retinal Cone Photoreceptor Cells / Q000378:metabolism / Q000473:pathology*; D059470:Tetraspanins; D014364:Tryptophan / Q000378:metabolism
D050976:Basic-Leucine Zipper Transcription Factors; D005136:Eye Proteins; D008565:Membrane Proteins; C084884:Nrl protein, mouse; D064531:Peripherins; C578996:Prph2 protein, mouse; C081477:Rom1 protein, mouse; D059470:Tetraspanins; D014364:Tryptophan; D001120:Arginine