Phenotypes for Rab28 MGI:6360455 MGI Mouse

short photoreceptor outer segment ( J:267522 )

• progressive retinal outer segment shortening, with outer segment lengths reduced to 69, 65, and 50% at 3, 6, and 13 months, respectively

abnormal retina cone cell morphology ( J:267522 )

• the number of cone outer segment phagosomes is reduced in the retina, with a 5-fold reduction in phagosome counts

• visual pigments ML-opsin and S-opsin are mislocalized in part to the inner segment, outer nuclear layer, and outer plexiform layer of cones

• however, rod phagosome density is similar to that in wild-type mice

• 1 month old retinas show elongated cones with disorganized distal membranes

abnormal retina cone cell outer segment morphology ( J:267522 )

• at the RPE/photoreceptor interface, RPE microvilli-wrapped structures filled with distorted membrane stacks or vacuolar membranes are seen; these structures appear in different shapes indicating buildup of materials at the outer segment tip

• cone outer segment distal tips are filled with vacuoles and/or distorted membranes

long retina cone cell outer segment ( J:267522 )

• cones have elongated outer segment, stretching toward the apical retinal pigment epithelium (RPE) edge, and enlarged outer segment tips

• slight elongation of cone outer segment and occasional outer segment tip enlargement are first seen shortly after eye opening around P12

• cone outer segments are on average 43% longer at 1 month of age

retina cone cell degeneration ( J:267522 )

• cone number is slightly reduced at 1 month but severely reduced at 3 months, and very few cones at 13 months indicating fast degeneration of cones

• cone densities are reduced to 88, 71, 35, and 12% of controls at 1, 3, 6, and 13 months, respectively

abnormal retina pigmentation ( J:267522 )

• increase in retinal pigment epithelium pigment deposits

abnormal retina outer nuclear layer thickness ( J:267522 )

• mild reduction of the outer nuclear layer (ONL) thickness

• ONL thickness in the central retina is reduced to 87, 78, and 73% of controls by 3, 6, and 13 months of age, respectively

increased susceptibility to age-related retinal degeneration ( J:267522 )

• progressive retina degeneration, with a gradual reduction of retinal outer segment length and outer nuclear layer thickness and a more rapid cone degeneration

decreased a-wave amplitude ( J:267522 )

• scotopic a-wave amplitudes are reduced to about 70% of control at 3 months

• scotopic a-wave amplitude declines slowly starting at 1 month and is 42% of wild-type levels by 13 months

decreased b-wave amplitude ( J:267522 )

• photopic b-wave amplitudes are reduced to less than 50% of control at 3 months

• photopic ERGs decline faster, being 65% of control at 1 month and undetectable at 13 months