Mruthinti Shyamala, Capito Nicholas, Sood Ajay, Buccafusc Jerry J
Veterans Administration Medical Center, Augusta, Georgia 30904-6285, USA.
Curr Alzheimer Res. 2007 Dec;4(5):581-6. doi: 10.2174/156720507783018325.
The receptor for advanced glycation end products (RAGE) binds amyloid peptides with high affinity. Soluble RAGE-like peptides and Abeta-like peptides occur in relatively high concentrations in the circulation of individuals with Alzheimer's disease. Protein complexes with epitopes for both Abeta and RAGE are also present. At physiological concentrations, forms of Abeta have different, but relatively low potencies as cytotoxicants in neural cells in culture. The purpose of this study was to determine whether a synthetic peptide complex composed of Abeta(1-42) and RAGE(23-54), a conserved N-terminal fragment of RAGE, exhibited increased cytotoxicity in comparison with the constituent peptides. Western analysis indicated that Abeta(1-42) and RAGE(23-54) remained primarily in their original low molecular weight states (4-6 kDa) during the maintenance of the individual peptides (37 degrees C) in water from 1 to 4 weeks. In contrast, over the same maintenance periods the combined Abeta(1-42) and RAGE(23-54) peptides shifted to higher molecular weight complexes (up to 80-120 kDa). Protein complexes of similar molecular weights with epitopes for Abeta and RAGE antibodies were identified in human plasma. Incubation of differentiated PC-12 cells with 10-100 microM Abeta(1-42) or with RAGE(23-54) resulted in concentration-dependent decreases in cell viability. The cytotoxicity of each peptide was slightly enhanced by the progressive maintenance of Abeta(1-42) and RAGE(23-54) in water over 3 weeks prior to the assay. Under the same conditions, the Abeta(1-42) - RAGE(23-54) complex became significantly more cytotoxic. These results suggest that the formation of soluble Abeta-RAGE complexes in Alzheimer's disease could represent a mechanism for enhancing the neurotoxicity of amyloid peptides.
晚期糖基化终末产物受体（RAGE）能与淀粉样肽高亲和力结合。可溶性RAGE样肽和β-淀粉样蛋白（Aβ）样肽在阿尔茨海默病患者的循环系统中浓度相对较高。同时也存在具有Aβ和RAGE表位的蛋白质复合物。在生理浓度下，不同形式的Aβ作为培养神经细胞中的细胞毒性剂，具有不同但相对较低的效力。本研究的目的是确定由Aβ（1-42）和RAGE（23-54）（RAGE保守的N端片段）组成的合成肽复合物与组成肽相比，是否表现出增强的细胞毒性。蛋白质印迹分析表明，在将单个肽（37℃）于水中保存1至4周期间，Aβ（1-42）和RAGE（23-54）主要保持其原始的低分子量状态（4-6 kDa）。相反，在相同的保存期内，组合的Aβ（1-42）和RAGE（23-54）肽转变为更高分子量的复合物（高达80-120 kDa）。在人血浆中鉴定出具有Aβ和RAGE抗体表位的类似分子量的蛋白质复合物。用10-100μM的Aβ（1-42）或RAGE（23-54）孵育分化的PC-12细胞导致细胞活力呈浓度依赖性下降。在测定前3周，将Aβ（1-42）和RAGE（23-54）在水中逐步保存，可使每种肽的细胞毒性略有增强。在相同条件下，Aβ（1-42）-RAGE（23-54）复合物的细胞毒性显著增强。这些结果表明，阿尔茨海默病中可溶性Aβ-RAGE复合物的形成可能代表了一种增强淀粉样肽神经毒性的机制。
