The cone matrix sheath in the normal and diseased retina: cytochemical and biochemical studies of peanut agglutinin-binding proteins in cone and rod-cone degeneration.
The fate of the cone-associated extracellular domain, or cone matrix sheath (CMS), was examined in two canine models of hereditary retinal degeneration. The diseases, which affect cones selectively (cd = cone degeneration), or rods and cones temporally (prcd = progressive rod-cone degeneration), were examined biochemically (SDS-PAGE/lectin blots) and cytochemically (light microscopy) using peanut agglutinin lectin (PNA) to selectively label this domain and associated structures. Most of the cones had disappeared in the adult cd retina. In the remaining cones, PNA labeled the ectopically located somata and the CMSs that were present around severely diseased ones. Loss of cones resulted in background label in the IPM and the loss of the pedicle-associated label in the OPL. SDS-PAGE of retinal extracts showed that all the major classes of the lower molecular weight PNA-binding proteins were present, but only the 40- and 60-kD bands remained prominent. Because of the selectivity of the cd mutation, this suggests considerable heterogeneity within the various size classifications of the retinal PNA-binding glycoproteins. In prcd, CMSs were normal at a time when cones were structurally normal and disease was limited to the rod outer segments. The CMSs remained intact during the degenerative phase of the disease, and only became compressed in association with the collapse and narrowing of the photoreceptor layer; CMS labeling was lost with disappearance of the cone inner segment. The lectin biochemical results were normal until 1.7 years of age; thereafter, there was a decreased prominence of all major bands. Because of spatial heterogeneity in disease severity, it was not possible to correlate the lectin biochemical and cytochemical results in prcd.
Long
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KO
Section of Medical Genetics, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104.
Aguirre
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GD
D000818:Animals; D010367:Arachis; D004195:Disease Models, Animal; D004285:Dogs; D005110:Extracellular Space; D006651:Histocytochemistry; D008856:Microscopy, Fluorescence; D010786:Photoreceptor Cells / Q000473:pathology*; D011975:Receptors, Mitogen / Q000378:metabolism*; D012162:Retinal Degeneration / Q000378:metabolism / Q000473:pathology; D012174:Retinitis Pigmentosa / Q000378:metabolism / Q000473:pathology*
D011975:Receptors, Mitogen; C038223:peanut agglutinin receptor