Cathepsin D Variants Associated With Neurodegenerative Diseases Show Dysregulated Functionality and Modified α-Synuclein Degradation Properties.
Cathepsin D Variants Associated With Neurodegenerative Diseases Show Dysregulated Functionality and Modified α-Synuclein Degradation Properties.
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DOI：
10.3389/fcell.2021.581805
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发表时间：
2021
影响因子：
5.5
通讯作者：
Zunke F
中科院分区：
文献类型：
--
作者：
Bunk J;Prieto Huarcaya S;Drobny A;Dobert JP;Walther L;Rose-John S;Arnold P;Zunke F
组织蛋白酶D（CTSD）是一种溶酶体蛋白酶，其对于各种底物的降解是重要的，所述底物包括疾病相关蛋白如α-突触核蛋白（α-syn）、淀粉样前体蛋白（APP）和tau，如果不能有效降解，则所有这些都倾向于聚集。因此，CTSD基因内的遗传变异与神经退行性疾病如帕金森病和阿尔茨海默病（PD，AD）以及溶酶体储存障碍神经元蜡样脂褐质沉积症10型（NCL 10）相关并不奇怪。虽然最近的研究表明，自噬途径内通过CTSD的底物降解的分子依赖性，只有很少的溶酶体CTSD功能在疾病发展中的确切作用所知。我们对患者基因组测序数据中发现的11个致病CTSD点突变进行了生化、细胞和结构分析，以了解它们在神经退行性变中的作用。在过表达分析中分析这些CTSD变体的细胞定位、成熟和酶活性。此外，对于PD相关突变体，监测α-syn的细胞内降解。总之，我们的结果表明，NCL 10相关的CTSD变体在溶酶体成熟和酶活性方面显著受损，而AD和PD相关的变体似乎相当不受影响，表明正常成熟和溶酶体存在。有趣的是，PD相关的CTSD变体（A239 V）表现出增加的酶活性，伴随着增强的α-syn降解。通过利用分子动力学模拟（MDS）的结构分析，我们确定了一个环内的催化中心附近的结构变化，导致更高的灵活性和潜在的加速底物交换速率。我们的数据揭示了CTSD在疾病发展中的作用，并有助于了解酶功能的结构调节，这可用于靶向CTSD激活。由于CTSD的降解功能，这种酶对于处理神经退行性疾病中的蛋白质聚集体的治疗策略特别感兴趣。
Cathepsin D (CTSD) is a lysosomal protease important for the degradation of various substrates, including disease-associated proteins like α-synuclein (a-syn), amyloid precursor protein (APP) and tau, all of which tend to aggregate if not efficiently degraded. Hence, it is not surprising that genetic variants within the CTSD gene have been linked to neurodegenerative diseases, like Parkinson’s and Alzheimer’s disease (PD, AD), as well as the lysosomal storage disorder neuronal ceroid lipofuscinosis type-10 (NCL10). Although recent studies have shown the molecular dependence of substrate degradation via CTSD within autophagic pathways, only little is known about the precise role of lysosomal CTSD function in disease development. We here performed biochemical, cellular and structural analyses of eleven disease-causing CTSD point mutations found in genomic sequencing data of patients to understand their role in neurodegeneration. These CTSD variants were analyzed for cellular localization, maturation and enzymatic activity in overexpression analyses. Moreover, for PD-associated mutants, intracellular degradation of a-syn was monitored. In summary, our results suggest that NCL10-associated CTSD variants are significantly impaired in lysosomal maturation and enzymatic activity, whereas the AD- and PD-associated variants seemed rather unaffected, indicating normal maturation, and lysosomal presence. Interestingly, a PD-associated CTSD variant (A239V) exhibited increased enzymatic activity accompanied by enhanced a-syn degradation. By structural analyses of this mutant utilizing molecular dynamics simulation (MDS), we identified a structural change within a loop adjacent to the catalytic center leading to a higher flexibility and potentially accelerated substrate exchange rates. Our data sheds light onto the role of CTSD in disease development and helps to understand the structural regulation of enzymatic function, which could be utilized for targeted CTSD activation. Because of the degradative function of CTSD, this enzyme is especially interesting for therapeutic strategies tackling protein aggregates in neurodegenerative disorders.
影响因子：
2.6
作者：
Mo C;Peng Q;Sui J;Wang J;Deng Y;Xie L;Li T;He Y;Qin X;Li S
通讯作者：
Li S