THE BETA-SUBUNIT OF CYCLIC-GMP PHOSPHODIESTERASE MESSENGER-RNA IS DEFICIENT IN CANINE ROD CONE DYSPLASIA-1

Irish setter dogs affected with rod-cone dysplasia 1 have elevated levels of retinal cGMP resulting from deficient rod-specific cGMP phosphodiesterase (cGMP PDE) activity. We investigated the mRNAs coding for the three subunits of cGMP PDE and for the proteins involved in the activation/deactivation of this enzyme in the retinas of developing affected and control dogs. While the photoreceptor cells are viable in the diseased retinas, opsin, transducin alpha-1 and beta-1, 48 and 33 kd proteins, and cGMP PDE-alpha and gamma-mRNAs have normal transcript sizes and levels. In contrast, a different pattern of cGMP PDE-beta mRNAs with lower than normal concentrations is present in the developing affected retinas prior to degeneration. Our observations suggest that an abnormality involving cGMP PDE-beta expression is implicated in rod-cone dysplasia 1.