Yamaguchi Itaru, Suda Hironori, Tsuzuike Naoki, Seto Kouichi, Seki Masaharu, Yamaguchi Yukiya, Hasegawa Kazuhiro, Takahashi Naoki, Yamamoto Suguru, Gejyo Fumitake, Naiki Hironobu
Department of Pathology, Fukui Medical University, Fukui, Japan.
Kidney Int. 2003 Sep;64(3):1080-8. doi: 10.1046/j.1523-1755.2003.00167.x.
Although several kinds of evidence suggest that glycosaminoglycans (GAGs) and proteoglycans (PGs) may contribute to the development of beta2-microglobulin-related (Abeta2m) amyloidosis, the precise roles of these molecules for the development of Abeta2m amyloidosis are poorly understood.
We investigated the effects of GAGs and PGs on the depolymerization of Abeta2m amyloid fibrils at a neutral pH, as well as on the formation of the fibrils at an acidic pH in vitro, using fluorescence spectroscopy with thioflavin T and electron microscopy.
Depolymerization of Abeta2m amyloid fibrils at pH 7.5 at 37 degrees C was inhibited dose-dependently by the presence of some GAGs (heparin, dermatan sulfate, or heparan sulfate) or PGs (biglycan, decorin, or keratan sulfate proteoglycan). Electron microscopy revealed that a significant amount of Abeta2m amyloid fibrils remained in the reaction mixture with some lateral aggregation. Second, when monomeric beta2m was incubated with aggrecan, biglycan, decorin, or heparin at pH 2.5 at 37 degrees C for up to 21 days, the thioflavin T fluorescence increased depending on dose and time. Electron microscopy revealed the formation of rigid and straight fibrils similar to Abeta2m amyloid fibrils in beta2m incubated with biglycan for 21 days.
These results suggest that some GAGs and PGs could enhance the deposition of Abeta2m amyloid fibrils in vivo, possibly by binding directly to the surface of the fibrils and stabilizing the conformation of beta2m in the fibrils, as well as by acting as a scaffold for the polymerization of beta2m into the fibrils.
尽管有多种证据表明糖胺聚糖（GAGs）和蛋白聚糖（PGs）可能与β2-微球蛋白相关（Abeta2m）淀粉样变性的发生有关，但这些分子在Abeta2m淀粉样变性发生过程中的具体作用仍知之甚少。
我们使用硫黄素T荧光光谱法和电子显微镜，研究了GAGs和PGs在中性pH下对Abeta2m淀粉样纤维解聚的影响，以及在酸性pH下对体外纤维形成的影响。
在37℃、pH 7.5条件下，一些GAGs（肝素、硫酸皮肤素或硫酸乙酰肝素）或PGs（双糖链蛋白聚糖、核心蛋白聚糖或硫酸角质素蛋白聚糖）的存在剂量依赖性地抑制了Abeta2m淀粉样纤维的解聚。电子显微镜显示，反应混合物中仍有大量Abeta2m淀粉样纤维，并伴有一些侧向聚集。其次，当单体β2m在37℃、pH 2.5条件下与聚集蛋白聚糖、双糖链蛋白聚糖、核心蛋白聚糖或肝素孵育长达21天时，硫黄素T荧光随剂量和时间增加。电子显微镜显示，在与双糖链蛋白聚糖孵育21天的β2m中，形成了类似于Abeta2m淀粉样纤维的刚性直纤维。
这些结果表明，一些GAGs和PGs可能通过直接结合到纤维表面并稳定纤维中β2m的构象，以及作为β2m聚合成纤维的支架，从而增强体内Abeta2m淀粉样纤维的沉积。
