PURPOSE: To study mechanisms leading to photoreceptor degeneration in mouse models for autosomal dominant retinitis pigmentosa (adRP) based on the rhodopsin P23H mutation. METHODS: Mice of a transgenic line expressing a rhodopsin triple mutant, V20G, P23H, and P27L (GHL), were mated with rhodopsin (rho) knockout mice. Littermates of various ages and genotypes (GHL+rho+/+, GHL+rho+/-, and GHL+rho-/-) were examined for outer nuclear layer thickness and outer segment formation (histology), fate of mutant rhodopsin (immunocytochemistry), and photoreceptor function (electroretinogram; ERG). RESULTS: Mice expressing GHL-rhodopsin in the absence of wild-type rhodopsin had severe retinopathy, which was nearly complete by postnatal day (P)30. GHL-rhodopsin formed homodimers nearly exclusively on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, whereas wild-type rhodopsin predominantly formed monomers. Expression level of mutant rhodopsin in predegenerate (P10) GHL+rho-/- retinas was low, approximately 10% to 25% of normal levels. No elaboration of disc membrane or outer segment formation was observed at any time point examined. The mutant rhodopsin was found mostly in perinuclear locales (endoplasmic reticulum; ER) as evidenced by colocalization using the antibodies Rho1D4 and calnexin-NT. CONCLUSIONS: GHL-rhodopsin dimerizes, localizes to the ER, and fails to transport and support outer segment formation. Additionally, the mutant protein does not support a scotopic ERG a-wave and accelerates photoreceptor degeneration over that occurring with the rhodopsin knockout alone. These findings indicate a cytotoxic effect of the mutant protein, probably elicited by an unfolded protein response.
PURPOSE: To study mechanisms leading to photoreceptor degeneration in mouse models for autosomal dominant retinitis pigmentosa (adRP) based on the rhodopsinP23H mutation. METHODS:Mice of a transgenic line expressing a rhodopsin triple mutant, V20G, P23H, and P27L (GHL), were mated with rhodopsin (rho) knockout mice. Littermates of various ages and genotypes (GHL+rho+/+, GHL+rho+/-, and GHL+rho-/-) were examined for outer nuclear layer thickness and outer segment formation (histology), fate of mutant rhodopsin (immunocytochemistry), and photoreceptor function (electroretinogram; ERG). RESULTS:Mice expressing GHL-rhodopsin in the absence of wild-type rhodopsin had severe retinopathy, which was nearly complete by postnatal day (P)30. GHL-rhodopsin formed homodimers nearly exclusively on sodium dodecyl sulfate-polyacrylamide gel electrophoresis gels, whereas wild-type rhodopsin predominantly formed monomers. Expression level of mutant rhodopsin in predegenerate (P10) GHL+rho-/- retinas was low, approximately 10% to 25% of normal levels. No elaboration of disc membrane or outer segment formation was observed at any time point examined. The mutant rhodopsin was found mostly in perinuclear locales (endoplasmic reticulum; ER) as evidenced by colocalization using the antibodies Rho1D4 and calnexin-NT. CONCLUSIONS: GHL-rhodopsin dimerizes, localizes to the ER, and fails to transport and support outer segment formation. Additionally, the mutant protein does not support a scotopic ERG a-wave and accelerates photoreceptor degeneration over that occurring with the rhodopsin knockout alone. These findings indicate a cytotoxic effect of the mutant protein, probably elicited by an unfolded protein response.
Authors: Haoyu Mao; Marina S Gorbatyuk; Brian Rossmiller; William W Hauswirth; Alfred S Lewin Journal: Hum Gene Ther Date: 2012-03-28 Impact factor: 5.695
Authors: Tomas S Aleman; Artur V Cideciyan; Alexander Sumaroka; Elizabeth A M Windsor; Waldo Herrera; D Alan White; Shalesh Kaushal; Anjani Naidu; Alejandro J Roman; Sharon B Schwartz; Edwin M Stone; Samuel G Jacobson Journal: Invest Ophthalmol Vis Sci Date: 2008-04 Impact factor: 4.799
Authors: Vanda S Lopes; David Jimeno; Kornnika Khanobdee; Xiaodan Song; Bryan Chen; Steven Nusinowitz; David S Williams Journal: Mol Biol Cell Date: 2010-10-06 Impact factor: 4.138