The C-terminal α-helices of mammalian Hsc70 play a critical role in the stabilization of α-synuclein binding and inhibition of aggregation
The C-terminal α-helices of mammalian Hsc70 play a critical role in the stabilization of α-synuclein binding and inhibition of aggregation
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DOI：
10.1016/j.ijbiomac.2015.10.089
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发表时间：
2016-02-01
影响因子：
8.2
通讯作者：
Ladjimi, Moncef
中科院分区：
文献类型：
--
作者：
Chaari, Ali;Eliezer, David;Ladjimi, Moncef
蛋白质错误折叠，随后聚集和淀粉样蛋白形成是许多流行疾病的潜在病理标志，包括帕金森病（PD），阿尔茨海默病（AD）和2型糖尿病（T2D）。在PD的情况下，α -突触核蛋白（α -syn）的聚集已被证明具有高度的细胞毒性，并在多巴胺能细胞的死亡中发挥关键作用。因此，抑制聚集过程可能被认为是治疗干预的一个有吸引力的途径。在这方面，分子伴侣，已知促进适当折叠的蛋白质，能够抑制蛋白质聚集，从而防止淀粉样蛋白的形成。在这项工作中，本研究使用不同的方法研究了组成性表达的伴侣蛋白Hsc70及其不同结构域对α -syn聚集的影响。结果表明，单独的c端结构域（残基386-646）通过增加α -syn寡聚核形成的滞后期，与整个Hsc70蛋白一样有效地抑制α -syn聚集，这表明伴侣蛋白与α -syn单体和/或小聚集体相互作用并稳定它们。已知c端螺旋（残基510-646）在伴侣蛋白的肽结合位点上起锁定靶肽配体的作用，而c端螺旋的缺失极大地降低了α -syn聚集的抑制效率，这表明这些螺旋在稳定Hsc70与α -syn之间的相互作用中起着至关重要的作用。此外，Hsc70及其结构域对聚集的影响似乎与细胞毒性的影响相关，通过不同程度地减少α -syn毒性物种的比例。总之，这些结果提示了一种机制，其中抑制突触核蛋白聚集是单体突触核蛋白与伴侣蛋白结合的结果，就像任何单体靶向未折叠蛋白或肽与伴侣蛋白结合一样。(C) 2015 Elsevier B.V.版权所有
Protein misfolding, followed by aggregation and amyloid formation is an underlying pathological hallmark in a number of prevalent diseases, including Parkinson's (PD), Alzheimer's (AD) and Type 2 diabetes (T2D). In the case of PD, the aggregation of alpha-synuclein protein (alpha-syn) has been shown to be highly cytotoxic and to play a key role in the death of dopaminergic cells. Thus, inhibition of the aggregation process may be considered as an attractive avenue for therapeutic intervention. In this respect, molecular chaperones, known to promote proper folding of proteins, are able to inhibit protein aggregation thus preventing amyloid formation. In this work, the effect of the constitutively expressed chaperone Hsc70 and its various domains on alpha-syn aggregation have been investigated using different approaches. The results show that the C-terminal domain alone (residues 386-646) is as efficient in inhibiting alpha-syn aggregation as the entire Hsc70 protein, by increasing the lag phase for alpha-syn oligomeric nucleus formation, suggesting that the chaperone interacts with and stabilizes alpha-syn monomers and/or small aggregates. Deletion of the C-terminal helices (residues 510-646), which are known to play the role of a lid locking target peptide ligands in the peptide-binding site of the chaperone, strongly reduced the efficiency of inhibition of alpha-syn aggregation indicating that these helices play an essential in stabilizing the interaction between Hsc70 and alpha-syn. Furthermore, the effects of Hsc70 and its structural domains on aggregation appear to correlate with those on cytotoxicity, by reducing the fraction of alpha-syn toxic species to various degrees. Together these results suggest a mechanism in which inhibition of synuclein aggregation is the result of monomeric synuclein binding to the chaperone as any monomeric target unfolded protein or peptide binding to the chaperone. (C) 2015 Elsevier B.V. All rights reserved.