NIH Research Festival
The SERPINF1 gene encodes the retinoprotective pigment epithelium-derived factor (PEDF). Photoreceptor cells express the PNPLA2 gene for its receptor PEDF-R, which is responsible for PEDF-mediated neurotrophic activities. To determine whether the PEDF/PEDF-R axis plays a regulatory role in photoreceptor structure and function, we characterized photoreceptors deficient in PEDF and PEDF-R.
CRISPR Pnpla2 knock-out mouse was crossbred with Serpinf1 null, and three genotypes were generated: wild type, Serpinf1+/-/Pnpla2-/- and Serpinf1-/-/Pnpla2-/-. Gene expression was determined in dissected retinas by RT-PCR. Mice were evaluated for electroretinography (ERG), fundoscopy and autofluorescence angiography. Whole eyes were enucleated and processed for histology, immunofluorescence, TUNEL, confocal microscopy, and transmission electron microscopy.
At 3 months of age, Serpinf1+/-/Pnpla2-/- and Serpinf1-/-/Pnpla2-/- mice had decreased and undetectable retinal Serpinf1, respectively, relative to their Serpinf1+/+/Pnpla2+/+ littermate controls and both had undetectable Pnpla2 expression levels. The Serpinf1+/-/Pnpla2-/- mice had higher lipid droplet density in their retinal pigment epithelium and Bruch‚Äôs membrane and the vasculature was more ectatic relative to controls. The Serpinf1-/-/Pnpla2-/- photoreceptors had morphological abnormalities. The ERG a- and b-waves of Serpinf1+/-/Pnpla2-/- and Serpinf1-/-/Pnpla2-/- mice were attenuated relative to controls. Loss of both PEDF and PEDF-R caused retinas to have thinner outer nuclear layers with TUNNEL positive photoreceptor cells, as well as decreased levels of rhodopsin, opsin, PKCŒ±, and synaptophysin compared to controls.
Ablation of both PEDF and PEDF-R in mice causes defects in photoreceptor development resulting in suboptimal photoreceptor performance and increases in lipid accumulation. These data identify the PEDF/PEDF-R axis as a critical component for photoreceptor structure and function.
Scientific Focus Area: Molecular Biology and Biochemistry
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