Mechanism of Amylin Fibrillization Enhancement by Heparin
Mechanism of Amylin Fibrillization Enhancement by Heparin
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DOI：
10.1074/jbc.m110.215814
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发表时间：
2011-07-01
影响因子：
4.8
通讯作者：
Alexandrescu, Andrei T.
中科院分区：
文献类型：
--
作者：
Jha, Suman;Patil, Sharadrao M.;Alexandrescu, Andrei T.
我们表征了胰淀素与确定长度的肝素片段的相互作用，所述肝素片段模拟了与2型糖尿病中发现的淀粉样蛋白沉积相关的糖胺聚糖链。肝素片段与单体胰淀素带正电荷的N-末端一半的结合取决于带负电荷的胰淀素的浓度，但与寡糖长度无关。相比之下，胰淀素原纤维形成对肝素片段长度具有S形依赖性，对于长于4个单体的寡糖观察到增强，并且超过12个单体的影响趋于平稳。长度依赖性表明肝素的带负电荷的螺旋结构静电地补充了纤维状胰淀素交叉β结构的带正电荷的表面。荧光共振能量转移和全内反射荧光显微镜实验表明，肝素与胰淀素原纤维，而不是提高原纤维催化。含有两个或八个糖单体的短肝素片段保护胰淀素对胰腺β细胞的MIN 6小鼠细胞模型的细胞毒性。
We characterized the interaction of amylin with heparin fragments of defined length, which model the glycosaminoglycan chains associated with amyloid deposits found in type 2 diabetes. Binding of heparin fragments to the positively charged N-terminal half of monomeric amylin depends on the concentration of negatively charged saccharides but is independent of oligosaccharide length. By contrast, amylin fibrillogenesis has a sigmoidal dependence on heparin fragment length, with an enhancement observed for oligosaccharides longer than four monomers and a leveling off of effects beyond 12 monomers. The length dependence suggests that the negatively charged helical structure of heparin electrostatically complements the positively charged surface of the fibrillar amylin cross-beta structure. Fluorescence resonance energy transfer and total internal reflection fluorescence microscopy experiments indicate that heparin associates with amylin fibrils, rather than enhancing fibrillogenesis catalytically. Short heparin fragments containing two-or eight-saccharide monomers protect against amylin cytotoxicity toward a MIN6 mouse cell model of pancreatic beta-cells.