Department of Pharmaceutical Sciences, One Medical Center Drive, West Virginia University, Morgantown, WV, 26506-9193, USA.
Department of Ophthalmology and Visual Sciences, Eye Institute, One Medical Center Drive, West Virginia University, Morgantown, WV, 26506-9193, USA.
Sci Rep. 2020 Oct 21;10(1):17885. doi: 10.1038/s41598-020-74628-2.
Progressive rod-cone degeneration (PRCD) is a small protein localized to photoreceptor outer segment (OS) disc membranes. Several mutations in PRCD are linked to retinitis pigmentosa (RP) in canines and humans, and while recent studies have established that PRCD is required for high fidelity disc morphogenesis, its precise role in this process remains a mystery. To better understand the part which PRCD plays in disease progression as well as its contribution to photoreceptor OS disc morphogenesis, we generated a Prcd-KO animal model using CRISPR/Cas9. Loss of PRCD from the retina results in reduced visual function accompanied by slow rod photoreceptor degeneration. We observed a significant decrease in rhodopsin levels in Prcd-KO retina prior to photoreceptor degeneration. Furthermore, ultrastructural analysis demonstrates that rod photoreceptors lacking PRCD display disoriented and dysmorphic OS disc membranes. Strikingly, atomic force microscopy reveals that many disc membranes in Prcd-KO rod photoreceptor neurons are irregular, containing fewer rhodopsin molecules and decreased rhodopsin packing density compared to wild-type discs. This study strongly suggests an important role for PRCD in regulation of rhodopsin incorporation and packaging density into disc membranes, a process which, when dysregulated, likely gives rise to the visual defects observed in patients with PRCD-associated RP.
进行性视锥-视杆细胞变性（PRCD）是一种定位于光感受器外节（OS）盘膜的小蛋白。PRCD 的几种突变与犬和人类的色素性视网膜炎（RP）有关，尽管最近的研究已经确定 PRCD 是高保真盘形发生所必需的，但它在这个过程中的精确作用仍然是个谜。为了更好地了解 PRCD 在疾病进展中的作用及其在光感受器 OS 盘形发生中的贡献，我们使用 CRISPR/Cas9 生成了 Prcd-KO 动物模型。视网膜中 PRCD 的缺失导致视觉功能下降，并伴有缓慢的视杆细胞变性。我们观察到 Prcd-KO 视网膜中的视紫红质水平在光感受器变性之前显著降低。此外，超微结构分析表明，缺乏 PRCD 的视杆细胞显示出定向和畸形的 OS 盘膜。引人注目的是，原子力显微镜显示，与野生型盘相比，Prcd-KO 视杆神经元中的许多盘膜不规则，含有较少的视紫红质分子和降低的视紫红质包装密度。这项研究强烈表明 PRCD 在调节视紫红质掺入和包装密度到盘膜中的重要作用，当这个过程失调时，可能会导致与 PRCD 相关的 RP 患者观察到的视觉缺陷。
