天然小分子化合物对神经退行性疾病相关蛋白异常聚集及神经毒性的干预作用

发布时间：2018-04-22 05:22

本文选题：β-淀粉样多肽 + α-突触核蛋白　；参考：《复旦大学》2013年博士论文

【摘要】：阿尔兹海默病和帕金森病严重威害人类健康。人们研究它们的发病机理发现,它们分别与p淀粉样(Aβ)多肽和a突触核(AS)蛋白的错误折叠和聚集密切相关。由于错误折叠和聚集,这些蛋白从正常生理状态下可溶性单体聚集成致病的可溶性的毒性聚集体和不可溶性淀粉样纤维,伴随着组织损伤和疾病的产生。因此,人们开始尝试从新的角度分析、研究和治疗AD,例如寻找可抑制寡聚体生成的化合物,或将已形成的纤维解聚成无毒性的聚集体而非有毒性的纤维前体。然而,目前关于这类化合物的研究报导尚不充分,这些化合物的作用机理仍不清楚。近年研究发现,金属离子能引发Ap多肽和AS蛋白构象转变,诱导它们形成毒性聚集体。我们设想：可寻找有效的金属离子络合剂,通过其对金属离子的捕捉作用,抑制金属离子与蛋白的相互作用,减少金属离子诱导蛋白纤维化聚集和神经毒性。尽管对于神经退性疾病的治疗目前尚无临床根治性药物,但一些天然小分子化合物因潜在用于治疗此类疾病而被重视。在这些天然小分子化合物中,姜黄素可以与金属离子和神经退行性疾病相关蛋白发生相互作用。然而,目前关于姜黄素与金属离子共同干预下对Ap多肽和AS蛋白的纤维化和神经毒性的影响报导甚少。此外,海藻糖因显著抑制Ap多肽聚集引起了重点关注。基于AS蛋白与Ap多肽纤维化动力学机理的相似性,我们推测海藻糖亦可能抑制AS蛋白的聚集而可能潜在地用于治疗PD。本文试图通过研究姜黄素对金属离子诱导的蛋白聚集和神经毒性的干预作用以及海藻糖对AS蛋白聚集和神经毒性的影响,探索这些小分子化合物在神经退行性疾病中的预防与治疗作用机理,为开发它们为治疗神经退行性疾病新药提供理论基础。本文的主要发现如下： (1)姜黄素对铝(Ⅲ)离子和铁(Ⅲ)离子诱导丝素蛋白构象转变的干预作用基于丝素蛋白与神经退行性疾病相关蛋白的相似性,我们采用丝素蛋白为模型蛋白,研究姜黄素对铁离子和铝离子诱导的蛋白构象转变的影响。研究发现,铁离子和铝离子均能明显促进丝素蛋白构象向p-折叠转变；姜黄素因对金属离子具有强络合能力,而抑制金属离子诱导丝素蛋白构象向p-折叠转变的作用。有意义的是,本章研究进一步发现,当[Al(Ⅲ)]/[curcumin]混合比介于1：1至1：2时,形成的Al(Ⅲ)-curcumin络合物,不仅可以有效抑制丝素蛋白β-折叠的形成,而且可将已形成的ê-折叠构象解折叠成无规卷曲构象。 (2)姜黄素对铝(Ⅲ)离子诱导Aβ42多肽聚集及神经毒性的抑制作用铝(Ⅲ)能明显促进Aβ42多肽纤维化,增加Aβ42多肽的神经毒性,而姜黄素能抑制此过程。此外,姜黄素因对金属离子具有强络合能力,不仅可抑制金属离子诱导Aβ42纤维化作用,而且形成的铝(Ⅲ)—姜黄素络合物可将已形成的Aβ42纤维解聚集成低毒性的无定形聚集体。 (3)海藻糖对野生型和A53T突变型α-突触核蛋白纤维化聚集的干预作用海藻糖与野生型AS蛋白共孵育时,在孵育前期,海藻糖诱导形成较大的野生型AS无定形聚集体,在孵育后期,这些预形成的较大无定形聚集体被解聚成小的非折叠态的无定形聚集体甚至单体。此外,当存在低浓度海藻糖干预时,海藻糖虽不能有效抑制A53T突变型AS原纤维的形成,但在孵育后期可将已形成的A53T突变型AS原纤维解聚集成可溶性的非折叠态聚集体甚至单体。当存在高浓度海藻糖干预时,海藻糖通过稳定A53T-AS寡聚体和原丝结构,显著抑制A53T-AS纤维的形成。 (4)海藻糖和姜黄素干预野生型和A53T突变型α-突触核蛋白在转基因PC12细胞模型中的过表达和细胞毒性浓度低于1mM的海藻糖以及姜黄素与铝以1：1混合时生成的络合物,能明显抑制野生型AS和A53T突变型AS蛋白在转基因PC12细胞内的过表达,且能抑制野生型AS和A53T突变型AS在细胞内的毒性,提高细胞活力。此外,姜黄素与铝以1：1混合时,生成的络合物,能明显抑制双氧水和铝离子诱导的AS过表达和神经毒性。本文研究表明,铝(Ⅲ)—姜黄素络合物和海藻糖可能是潜在的神经退行疾病治疗药物,值得进一步研究和证实。
[Abstract]:Alzheimer's and Parkinson's disease seriously harm human health. The study of their pathogenesis has found that they are closely related to the misfolding and aggregation of the P amyloid (A beta) polypeptide and the a synaptic nucleus (AS) protein. Sexual toxic aggregates and insoluble amyloid fibers are accompanied by tissue damage and disease. Therefore, people have begun to attempt to analyze and treat AD from a new perspective, such as finding compounds that can inhibit oligomers, or depolymerize the formed fibers into nontoxic aggregates rather than toxic fibrous precursors. At present, the research reports on these compounds are not enough, and the mechanism of these compounds is still unclear.
Recent studies have found that metal ions can induce the conformation transition of Ap peptides and AS proteins and induce them to form toxic aggregates. We assume that an effective metal ion complexing agent can be found to inhibit the interaction of metal ions with proteins by its capture of metal ions and reduce the aggregation of fibrin induced proteins and nerves in metal ions. Toxicity.
Although there are no clinical radical drugs for the treatment of neurodegenerative diseases, some natural small molecular compounds are valued for their potential for the treatment of such diseases. In these natural small molecular compounds, curcumin can interact with metal ions and neurodegenerative diseases related proteins. However, Jiang Huang is currently concerned. There are few reports on the effects of Ap polypeptide and AS protein on the fibrosis and neurotoxicity of the peptide and the metal ions. In addition, trehalose is a major concern for inhibiting the aggregation of Ap polypeptide. Based on the similarity of the kinetic mechanism of the AS protein to the Ap polypeptide fibrosis, we speculate that the alga may also inhibit the aggregation of AS protein and possibly submersible. In the field for the treatment of PD.
The effect of curcumin on protein aggregation and neurotoxicity induced by curcumin and the effect of trehalose on AS protein aggregation and neurotoxicity are explored to explore the mechanism of the prevention and treatment of these small molecular compounds in neurodegenerative diseases, in order to develop new drugs for the treatment of neurodegenerative diseases. The main findings of this paper are as follows:
(1) the intervention of curcumin on the conformation transition of silk fibroin induced by aluminum (III) ions and iron (III) ions.
Based on the similarity between silk fibroin and neurodegenerative diseases, we used fibroin as model protein to study the effect of curcumin on the conformation of protein conformation induced by iron and aluminum ions. It was found that both iron and aluminum ions could obviously promote the transformation of the conformation of silk fibroin to p-, and curcumin was isolated from metal. It is significant that the Al (III) -curcumin complex formed when the [Al (III)]/[curcumin] mixture ratio is between 1:1 and 1:2, can not only effectively inhibit the formation of the fibroin beta - folding, but also can be used to inhibit the formation of the p- (III) -curcumin complex. The formed folded conformation is folded into a random conformation.
(2) curcumin inhibits the aggregation and neurotoxicity of A (42) peptide induced by aluminum (III) ion.
Aluminum (III) can obviously promote the fibrosis of A beta 42 polypeptide, increase the neurotoxicity of A beta 42 polypeptide, and curcumin can inhibit this process. In addition, curcumin can inhibit metal ions induced A beta 42 fibrosis due to metal ions, and the formed aluminum (III) curcumin complex can depolymerization the formed A beta 42 fiber. Integrated low toxic amorphous aggregates.
(3) trehalose intervention on fibroblast aggregation of wild-type and A53T mutant alpha synuclein
In the incubation period of trehalose and wild type AS protein, trehalose induced the formation of large wild type AS amorphous aggregates at the pre incubation period. In the late incubation period, these pre formed large amorphous aggregates were depolymerize into small unfolded amorphous aggregates and even monomers. It can effectively inhibit the formation of the A53T mutant AS fibrils, but in the late incubation period, the formed A53T mutated AS fibrils can be disassembled into soluble non folded aggregates or even monomers. When there is high concentration trehalose intervention, trehalose significantly inhibits the formation of A53T-AS fibers by stabilizing the A53T-AS oligomer and precursor structure.
(4) trehalose and curcumin interfere the overexpression and cytotoxicity of wild-type and A53T mutant alpha synuclein in transgenic PC12 cell models.
The complex of trehalose with a concentration of less than 1mM and the complex of curcumin and aluminum when mixed with 1:1 can obviously inhibit the overexpression of wild type AS and A53T mutated AS protein in the transgenic PC12 cells, and can inhibit the toxicity of the wild type AS and A53T mutants AS in the cells and increase the viability of the cells. The complex can inhibit AS overexpression and neurotoxicity induced by hydrogen peroxide and aluminum ions.
This study indicates that aluminum (III) - Curcumin complex and trehalose may be potential drugs for the treatment of neurodegenerative diseases, and deserve further study and confirmation.

【学位授予单位】：复旦大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：R742;R749.16

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