Khadka Nawal K, Hazen Preston, Akinola Oluwaseyi, Pu Xinzhu, Mainali Laxman
Department of Physics, Boise State University, Boise, Idaho, United States.
Biomolecular Sciences Graduate Program, Boise State University, Boise, Idaho, United States.
Invest Ophthalmol Vis Sci. 2025 Sep 2;66(12):8. doi: 10.1167/iovs.66.12.8.
The significant lens chaperone protein α-crystallin (αABc), comprised of αA-crystallin (αAc) and αB-crystallin (αBc) subunits, is found to form membrane-bound aggregates with age and cataract formation. However, the molecular basis for such aggregate formation is still unclear. Our research primarily aims to elucidate the effect of lipids (phospholipids and sphingolipids) and cholesterol (Chol) peroxidation on the aggregation of αAc, αBc, and αABc to bovine lens nuclear membrane (NM).
Lipid and Chol peroxidation was induced by a photosensitized peroxidation reaction, and topographical images of NM and oxidized-NM (Ox-NM) with and without αAc, αBc, or αABc were obtained using atomic force microscopy (AFM).
The percentage of membrane area occupied (PMAO) by αAc, αBc, or αABc aggregates on NMs was significantly smaller without lipid and Chol peroxidation. However, with NM lipid and Chol peroxidation, the PMAO of αAc, αBc, or αABc aggregates on the Ox-NM was significantly more extensive, and PMAO increased with an increase in lipid and Chol peroxidation. Large-size aggregates of αAc, αBc, or αABc on Ox-NM with the depressed central region for αAc and αABc aggregates on Ox-NM were observed to a greater extent with increased lipid and Chol peroxidation.
Lipid and Chol peroxidation induce membrane defects on NM, followed by extensive aggregation of αAc, αBc, and αABc on Ox-NM, suggests that lipid and Chol peroxidation promotes the aggregation of αAc, αBc, and αABc to Ox-NM, and the formation of such large aggregates likely promotes increased light scattering and cataract formation.
重要的晶状体伴侣蛋白α-晶状体蛋白（αABc）由αA-晶状体蛋白（αAc）和αB-晶状体蛋白（αBc）亚基组成，已发现其会随着年龄增长和白内障形成而形成膜结合聚集体。然而，这种聚集体形成的分子基础仍不清楚。我们的研究主要旨在阐明脂质（磷脂和鞘脂）和胆固醇（Chol）过氧化对αAc、αBc和αABc在牛晶状体核膜（NM）上聚集的影响。
通过光敏过氧化反应诱导脂质和Chol过氧化，使用原子力显微镜（AFM）获得有或没有αAc、αBc或αABc的NM和氧化NM（Ox-NM）的形貌图像。
在没有脂质和Chol过氧化的情况下，αAc、αBc或αABc聚集体在NM上占据的膜面积百分比（PMAO）显著较小。然而，随着NM脂质和Chol过氧化，αAc、αBc或αABc聚集体在Ox-NM上的PMAO显著更大，并且PMAO随着脂质和Chol过氧化的增加而增加。随着脂质和Chol过氧化的增加，在Ox-NM上观察到αAc、αBc或αABc的大尺寸聚集体，其中αAc和αABc聚集体在Ox-NM上的中心区域凹陷更为明显。
脂质和Chol过氧化诱导NM上的膜缺陷，随后αAc、αBc和αABc在Ox-NM上广泛聚集，这表明脂质和Chol过氧化促进αAc、αBc和αABc在Ox-NM上的聚集，并且这种大聚集体的形成可能促进光散射增加和白内障形成。
