Format

Send to

Choose Destination
Invest Ophthalmol Vis Sci. 2001 Mar;42(3):826-33.

Mutant rhodopsin transgene expression on a null background.

Author information

1
John A. Moran Eye Center, University of Utah Health Science Center, 50 North Medical Drive, Salt Lake City, UT 04132, USA. jfrederi@hsc.utah.edu

Abstract

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.

PMID:
11222546
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Silverchair Information Systems
Loading ...
Support Center