Identification of a nonsense mutation in the rod photoreceptor cGMP phosphodiesterase beta-subunit gene of the rd mouse.

Abstract

Retinal degeneration in the mouse mutant, rd, was previously shown to be a disorder of cyclic nucleotide metabolism involving a deficiency in the activity of the rod photoreceptor cGMP phosphodiesterase (PDE). We have characterized the normal and rd PDE (3-subunit gene, and their respective transcripts, by PCR and direct sequence analysis.We show that the gene consists of at least 22 exons ranging in size from 48 base pairs to several hundred base pairs, covering >25 kilobases. Within a 67-base-pair exon of the rd PDE (3-subunit gene, we identified a nonsense ochre mutation (a C -3 A transversion in codon 347) that truncates the normal gene product, eliminating more than one-half of the peptide chain, including the putative catalytic domain. The consequences of the truncation are consistent with the observed phenotypes in rd mice heterozygous and homozygous for the disorder. The nonsense mutation was also found in another related and in six unrelated strains displaying the rdphenotype, indicating that the rd allele arose from a single genetic event.The results strongly argue for the nonsense mutation being responsible for retinal degeneration in the rd mouse.

The Function of Guanylate Cyclase 1 and Guanylate Cyclase 2 in Rod and Cone Photoreceptors

“…This suggests that the recessive retinal degeneration in the rd1 mouse (53,54), which has high levels of cGMP due to an incapacitated PDE6, cannot be rescued by deletion of GCs.…”

Functional Analysis of the Rod Photoreceptor cGMP Phosphodiesterase α-Subunit Gene Promoter

“…The binding reaction was run on a nondenaturing 6% acrylamide gel in 0.5ϫ TBE for 2 h at 380 V. CrxHD-GST protein was purified on a glutathione affinity column as previously described (14) Real-time Quantitative PCR-Crx Ϫ/Ϫ mice were obtained from Dr. Connie Cepko (Department of Genetics, Harvard Medical School). The Crx Ϫ/Ϫ mouse was outcrossed to a congenic C57Bl/6 ϫ SJL hybrid strain that is ϩ/ϩ at the rd1 locus (6). The mice were bred to homozygosity for the Crx knockout allele and maintained for Ͼ6 generations.…”

Interaction of Aryl Hydrocarbon Receptor-interacting Protein-like 1 with the Farnesyl Moiety

“…Light stimulates phototransduction by activating PDE6AB to hydrolyze a second messenger cGMP and close cGMP-gated channels in the photoreceptor plasma membrane (19,20). Mutations in PDE6AB are known to cause retinal degeneration in humans and animal models by elevating intracellular cGMP concentration and triggering photoreceptor cell death (21)(22)(23)(24)(25). Thus, defective PDE6 function due to mutations in AIPL1 readily explains LCA4.…”