Oda T, Wals P, Osterburg H H, Johnson S A, Pasinetti G M, Morgan T E, Rozovsky I, Stine W B, Snyder S W, Holzman T F
Neurogerontology Division, Andrus Gerontology Center, University of Southern California, Los Angeles 90089-0191, USA.
Exp Neurol. 1995 Nov;136(1):22-31. doi: 10.1006/exnr.1995.1080.
Clusterin (apoJ), a multifunctional apolipoprotein made by cells in the brain and many other locations, is associated with aggregated amyloid beta-peptide (A beta) in senile and diffuse plaques of Alzheimer's disease (AD). We observed that purified human serum clusterin partially blocked the aggregation of synthetic A beta 1-42, as shown by centrifugal assays (14,000g x 10 min) and by atomic force (scanning probe) microscopy. Slowly sedimenting A beta complexes were formed in the presence of clusterin, which included aggregates > 200 kDa that resist dissociation by low concentrations of SDS. Clusterin enhanced the oxidative stress caused by A beta, as assayed by oxidative stress in PC12 cells with MTT, which is widely used to estimate neurotoxicity. These indications of enhanced neurotoxicity by the MTT assay were observed in the highly aggregated rapidly sedimenting fraction, but also in more slowly sedimenting "soluble" forms. This novel activity of slowly sedimenting A beta may enhance the neurotoxicity of A beta deposits in AD brains, because soluble complexes have a potential for diffusing to damage distal neurons.
簇集素（载脂蛋白J）是一种由大脑及许多其他部位的细胞产生的多功能载脂蛋白，与阿尔茨海默病（AD）老年斑和弥漫性斑块中的淀粉样β肽（Aβ）聚集物相关。我们观察到，纯化的人血清簇集素部分阻断了合成Aβ1-42的聚集，这通过离心测定法（14,000g×10分钟）和原子力（扫描探针）显微镜观察得以证实。在簇集素存在的情况下形成了沉降缓慢的Aβ复合物，其中包括大于200 kDa的聚集体，这些聚集体在低浓度十二烷基硫酸钠（SDS）作用下不会解离。通过广泛用于评估神经毒性的MTT法检测PC12细胞中的氧化应激发现，簇集素增强了Aβ引起的氧化应激。MTT法检测显示，这种增强神经毒性的迹象不仅在高度聚集且沉降迅速的部分中观察到，在沉降较慢的“可溶性”形式中也观察到。沉降缓慢的Aβ的这种新活性可能会增强AD大脑中Aβ沉积物的神经毒性，因为可溶性复合物有可能扩散至损伤远处的神经元。
