Fibril specific, conformation dependent antibodies recognize a generic epitope common to amyloid fibrils and fibrillar oligomers that is absent in prefibrillar oligomers.-猫眼课题宝

DOI：

10.1186/1750-1326-2-18

发表时间：

2007-09-26

期刊：

Molecular neurodegeneration

影响因子：

15.1

通讯作者：

中科院分区：

医学1区

文献类型：

作者：

Kayed R;Head E;Sarsoza F;Saing T;Cotman CW;Necula M;Margol L;Wu J;Breydo L;Thompson JL;Rasool S;Gurlo T;Butler P;Glabe CG

来源链接：

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2100048/?report=classic

淀粉样蛋白相关的退行性疾病与组织中错误折叠的蛋白质作为淀粉样蛋白原纤维的积累有关。在阿尔茨海默病（AD）中，淀粉样蛋白以几种不同类型的不溶性斑块沉积物、细胞内Aβ和可溶性寡聚物的形式积累，这些沉积物与其病理学意义之间的关系尚不清楚。构象依赖性抗体已被报道特异性识别淀粉样蛋白的不同组装状态，包括前原纤维寡聚体和原纤维。我们用Aβ42纤维的形态学均一群体免疫家兔。所得的免疫血清（OC）特异性识别原纤维，但不识别无规卷曲单体或前原纤维寡聚体，表明原纤维显示在前原纤维寡聚体中不存在的独特构象依赖性表位。原纤维表位也由其他类型的淀粉样蛋白的原纤维展示，表明该表位是多肽骨架的一般特征。原纤维特异性抗体还识别100，000 × G可溶性原纤维寡聚体，其大小范围从二聚体到蛋白质印迹上大于250 kDa。由OC识别的纤维状寡聚体在免疫学上不同于由A11识别的前纤维状寡聚体，即使它们的大小广泛重叠，表明大小不是寡聚体构象的可靠指标。对前原纤维寡聚体和原纤维的免疫应答不是序列特异性的，并且响应于用胰岛淀粉样多肽前原纤维寡聚体模拟物和原纤维的免疫而产生相同特异性的抗血清。原纤维特异性抗体染色人AD脑中所有类型的淀粉样蛋白沉积物。弥漫性淀粉样蛋白沉积物被抗原纤维抗体强烈染色，尽管它们是硫磺素S阴性的，这表明它们确实是原纤维构象。OC还染色II型糖尿病转基因小鼠模型中的胰岛淀粉样蛋白沉积物，证明其对淀粉样蛋白原纤维的一般特异性。由于原纤维特异性抗体是构象依赖性的，序列不依赖性的，并且识别与存在于前原纤维寡聚体中的表位不同的表位，因此它们可以具有检测和表征变性疾病中淀粉样蛋白原纤维和原纤维型寡聚体的积累的广泛用途。

Amyloid-related degenerative diseases are associated with the accumulation of misfolded proteins as amyloid fibrils in tissue. In Alzheimer disease (AD), amyloid accumulates in several distinct types of insoluble plaque deposits, intracellular Aβ and as soluble oligomers and the relationships between these deposits and their pathological significance remains unclear. Conformation dependent antibodies have been reported that specifically recognize distinct assembly states of amyloids, including prefibrillar oligomers and fibrils. We immunized rabbits with a morphologically homogeneous population of Aβ42 fibrils. The resulting immune serum (OC) specifically recognizes fibrils, but not random coil monomer or prefibrillar oligomers, indicating fibrils display a distinct conformation dependent epitope that is absent in prefibrillar oligomers. The fibril epitope is also displayed by fibrils of other types of amyloids, indicating that the epitope is a generic feature of the polypeptide backbone. The fibril specific antibody also recognizes 100,000 × G soluble fibrillar oligomers ranging in size from dimer to greater than 250 kDa on western blots. The fibrillar oligomers recognized by OC are immunologically distinct from prefibrillar oligomers recognized by A11, even though their sizes overlap broadly, indicating that size is not a reliable indicator of oligomer conformation. The immune response to prefibrillar oligomers and fibrils is not sequence specific and antisera of the same specificity are produced in response to immunization with islet amyloid polypeptide prefibrillar oligomer mimics and fibrils. The fibril specific antibodies stain all types of amyloid deposits in human AD brain. Diffuse amyloid deposits stain intensely with anti-fibril antibody although they are thioflavin S negative, suggesting that they are indeed fibrillar in conformation. OC also stains islet amyloid deposits in transgenic mouse models of type II diabetes, demonstrating its generic specificity for amyloid fibrils. Since the fibril specific antibodies are conformation dependent, sequence-independent, and recognize epitopes that are distinct from those present in prefibrillar oligomers, they may have broad utility for detecting and characterizing the accumulation of amyloid fibrils and fibrillar type oligomers in degenerative diseases.