Modulation of Aβ42 fibrillogenesis by glycosaminoglycan structure
Modulation of Aβ42 fibrillogenesis by glycosaminoglycan structure
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DOI：
10.1096/fj.09-153551
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发表时间：
2010-11-01
期刊：
影响因子：
4.8
通讯作者：
Fernandez-Busquets, Xavier
中科院分区：
文献类型：
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作者：
Jose Valle-Delgado, Juan;Alfonso-Prieto, Mercedes;Fernandez-Busquets, Xavier
淀粉样蛋白β（A β）肽在阿尔茨海默病发病和进展中的作用与可溶性A β物质的存在有关。硫酸化糖胺聚糖（GAG）促进A β原纤维形成并降低肽在神经元细胞培养物中的毒性，但尚未提供在分子水平上解释这些作用的令人满意的理由。我们已经使用圆二色谱，傅里叶变换红外光谱，荧光显微镜和光谱，蛋白酶消化，原子力显微镜（AFM），和分子动力学模拟表征的42个残基片段A β（42）与硫酸化糖胺聚糖，透明质酸，壳聚糖，聚（乙烯基硫酸酯）（PVS）的协会。我们的研究结果表明，稳定的A β（42）原纤维的形成是由具有负电荷的聚合物GAG促进的，这些负电荷与原纤维β-片层内分离A β（42）单体的4.8埃处于同一框内。将A β（42）与过量的硫酸化GAG和透明质酸一起孵育增加了淀粉样原纤维含量和对蛋白水解的抗性2- 5倍，而在阳离子多糖壳聚糖的存在下，A β（42）原纤维种类减少了25%，对蛋白酶降解的敏感性增加了约3倍。在PVS存在下获得中间稳定性的原纤维，PVS是一种比GAG具有更紧密堆积电荷的阴离子聚合物。通过AFM观察到由PVS诱导的A β（42）原纤维与在存在GAG和透明质酸的情况下获得的A β（42）原纤维之间的重要结构差异，而在与壳聚糖孵育后主要检测到前体原纤维形式。对于GAG和PVS，计算出的每个肽的结合能为-11.2至-13.5 kcal/mol，而对于壳聚糖，获得了显著较低的值-7.4 kcal/mol。总之，我们的数据表明了一种简单而直接的机制来解释GAG作为不溶性A β（42）纤维形成的增强剂的作用，这些纤维捕获可溶性毒性形式。Valle-Delgado，J. J.，Alfonso-Prieto，M.，de Groot，N.美国，文图拉，S.，Samitier，J.，罗维拉角Fernando-Busquets，X.糖胺聚糖结构对A β（42）纤维形成的调节。FASEB J.24，4250-4261（2010）。www.fasebj.org
The role of amyloid beta (A beta) peptide in the onset and progression of Alzheimer's disease is linked to the presence of soluble A beta species. Sulfated glycosaminoglycans (GAGs) promote A beta fibrillogenesis and reduce the toxicity of the peptide in neuronal cell cultures, but a satisfactory rationale to explain these effects at the molecular level has not been provided yet. We have used circular dichroism, Fourier transform infrared spectroscopy, fluorescence microscopy and spectroscopy, protease digestion, atomic force microscopy (AFM), and molecular dynamics simulations to characterize the association of the 42-residue fragment A beta(42) with sulfated GAGs, hyaluronan, chitosan, and poly(vinyl sulfate) (PVS). Our results indicate that the formation of stable A beta(42) fibrils is promoted by polymeric GAGs with negative charges placed in-frame with the 4.8-angstrom separating A beta(42) monomers within protofibrillar beta-sheets. Incubation of A beta(42) with excess sulfated GAGs and hyaluronan increased amyloid fibril content and resistance to proteolysis 2- to 5-fold, whereas in the presence of the cationic polysaccharide chitosan, A beta(42) fibrillar species were reduced by 25% and sensitivity to protease degradation increased similar to 3-fold. Fibrils of intermediate stability were obtained in the presence of PVS, an anionic polymer with more tightly packed charges than GAGs. Important structural differences between A beta(42) fibrils induced by PVS and A beta(42) fibrils obtained in the presence of GAGs and hyaluronan were observed by AFM, whereas mainly precursor protofibrillar forms were detected after incubation with chitosan. Computed binding energies per peptide from -11.2 to -13.5 kcal/mol were calculated for GAGs and PVS, whereas a significantly lower value of -7.4 kcal/mol was obtained for chitosan. Taken together, our data suggest a simple and straightforward mechanism to explain the role of GAGs as enhancers of the formation of insoluble A beta(42) fibrils trapping soluble toxic forms.-Valle-Delgado, J. J., Alfonso-Prieto, M., de Groot, N. S., Ventura, S., Samitier, J., Rovira, C., Fernandez-Busquets, X. Modulation of A beta(42) fibrillo-genesis by glycosaminoglycan structure. FASEB J. 24, 4250-4261 (2010). www.fasebj.org