Department of Biochemistry and Nutrition, Central Food Technological Research Institute, CSIR Unit, Mysore, India.
J Alzheimers Dis. 2011;24 Suppl 2:211-21. doi: 10.3233/JAD-2011-101965.
Parkinson's disease (PD) is a neurodegenerative disease with multiple etiologies. Advanced glycation end products (AGEs) accumulate in the aging brain and could be one of the reasons for age-related diseases like PD. Oxidative stress also leads to the formation of AGEs and may be involved in neurodegeneration by altering the properties of proteins. α-Synuclein is involved in pathogenesis of PD and there are limited studies on the role of AGE-α-synuclein in neurodegeneration. We studied the aggregation and DNA binding ability of AGE-α-synuclein in vitro. α-Synuclein is glycated using methylglyoxal and formation of AGE-α-synuclein is characterized using fluorescence studies, intrinsic tyrosine fluorescence, and fructosamine estimation. The results indicated that AGE-α-synuclein aggregates into smaller globular-like aggregates compared to fibrils formed with native α-synuclein. Further, it is found that AGE-α-synuclein induced conformational changes in scDNA from B-form to B-C-A mixed conformation. Additionally, AGE-α-synuclein altered DNA integrity as evidenced by the melting temperature, ethidium bromide, and DNAse I sensitivity studies. AGE-α-synuclein converted biphasic Tm to higher monophasic Tm. The Tm of AGE-α-synuclein-scDNA complex is more than that of native α-synuclein-scDNA complex, indicating that AGE-α-synuclein stabilized the uncoiled scDNA. AGE-α-synuclein could stabilize the uncoiled scDNA, as shown by the decrease in the number of ethidium bromide binding molecules per base pair of DNA. DNAse I sensitive studies indicated that both AGE-α-synuclein-scDNA and α-synuclein-scDNA are resistant to DNAse I digestion. The relevance of these findings to neuronal cell death is discussed.
帕金森病（PD）是一种具有多种病因的神经退行性疾病。晚期糖基化终产物（AGEs）在衰老的大脑中积累，可能是 PD 等与年龄相关疾病的原因之一。氧化应激也会导致 AGEs 的形成，并可能通过改变蛋白质的性质而参与神经变性。α-突触核蛋白参与 PD 的发病机制，关于 AGE-α-突触核蛋白在神经变性中的作用的研究有限。我们在体外研究了 AGE-α-突触核蛋白的聚集和 DNA 结合能力。使用甲基乙二醛使 α-突触核蛋白糖基化，并通过荧光研究、内在酪氨酸荧光和果糖胺估计来表征 AGE-α-突触核蛋白的形成。结果表明，与天然 α-突触核蛋白形成的纤维相比，AGE-α-突触核蛋白聚集成更小的球状聚集物。此外，发现 AGE-α-突触核蛋白诱导 scDNA 从 B 型构象向 B-C-A 混合构象发生构象变化。此外，AGE-α-突触核蛋白改变了 DNA 的完整性，这可以通过熔点、溴化乙锭和 DNAse I 敏感性研究来证明。AGE-α-突触核蛋白将双峰 Tm 转变为更高的单相 Tm。AGE-α-突触核蛋白-scDNA 复合物的 Tm 高于天然 α-突触核蛋白-scDNA 复合物的 Tm，这表明 AGE-α-突触核蛋白稳定了未卷曲的 scDNA。AGE-α-突触核蛋白可以稳定未卷曲的 scDNA，这可以从 DNA 每碱基对结合的溴化乙锭分子数量减少看出。DNAse I 敏感性研究表明，AGE-α-突触核蛋白-scDNA 和 α-突触核蛋白-scDNA 都对 DNAse I 消化具有抗性。讨论了这些发现与神经元细胞死亡的相关性。
