Verma Meenakshi, Girdhar Amandeep, Patel Basant, Ganguly Nirmal K, Kukreti Ritushree, Taneja Vibha
Genomics and Molecular Medicine, Institute of Genomics and Integrative Biology, Council of Scientific & Industrial Research (CSIR), New Delhi, India.
Department of Research, Sir Ganga Ram Hospital, New Delhi, India.
Front Mol Neurosci. 2018 Mar 13;11:75. doi: 10.3389/fnmol.2018.00075. eCollection 2018.
Interactions amongst different amyloid proteins have been proposed as a probable mechanism of aggregation and thus an important risk factor for the onset as well as progression of various neurodegenerative disorders including Alzheimer's, Parkinson's, Huntington's, and Amyotrophic Lateral Sclerosis. Evidences suggest that transthyretin (TTR), a plasma protein associated with transthyretin amyloidosis or familial polyneuropathy (FAP) interacts with heterologous amyloid proteins including amyloid beta and islet amyloid polypeptide. In addition, recent clinical studies have revealed the presence of systemic polyneuropathy associated with FAP mutations in patients with spinocerebral ataxia, amyotrophic lateral sclerosis, and new familial systematic prion disease. Hence, it is important to investigate the interactions amongst different amyloid proteins to gain better insight into the pathology of amyloid disorders. Yeast has been an excellent model system to study interaction/ cross-seeding between heterologous amyloid proteins, more because of presence of endogenous yeast prions. Here, we examined interactions of non-glutamine (non-Q)-rich transthyretin, with glutamine (Q)-rich yeast prion protein Sup35. We established aggregation of an engineered double (F87M/L110M) mutant M-TTR-GFP in yeast. This mutant is monomeric and readily formed aggregates compared to WT-TTR-GFP in yeast at acidic pH. Interestingly, aggregation of M-TTR-GFP was significantly enhanced in presence of [], an endogenous prion form of Sup35. Different variants of [] seeded M-TTR-GFP with different efficiencies and curing of [] (losing the prion form) in these strains reduced aggregation. Moreover, overexpression of prion domain of Sup35 fused to RFP (NM-RFP) also increased M-TTR-GFP aggregation. M-TTR-GFP and NM-RFP aggregates co-localized in perivacuolar and juxtranuclear region. Sup35 protein was even immunocaptured in M-TTR-GFP aggregates. However, M-TTR-GFP overexpression did not induce Sup35 aggregation. Thus, it appears to be a unidirectional interaction between these two amyloid proteins. However, no affect on M-TTR-GFP aggregation was observed due to another yeast prion, []. Our findings thus show the molecular interaction of transthyretin with yeast prion and support that sequence similarity is not the prime requirement for heterologous amyloid interactions.
不同淀粉样蛋白之间的相互作用被认为是一种可能的聚集机制,因此是包括阿尔茨海默病、帕金森病、亨廷顿病和肌萎缩侧索硬化症在内的各种神经退行性疾病发病和进展的重要风险因素。有证据表明,与转甲状腺素蛋白淀粉样变性或家族性多发性神经病(FAP)相关的血浆蛋白转甲状腺素蛋白(TTR)与包括淀粉样β蛋白和胰岛淀粉样多肽在内的异源淀粉样蛋白相互作用。此外,最近的临床研究表明,患有脊髓小脑共济失调、肌萎缩侧索硬化症和新的家族性系统性朊病毒病的患者中存在与FAP突变相关的系统性多发性神经病。因此,研究不同淀粉样蛋白之间的相互作用对于更好地了解淀粉样疾病的病理学很重要。酵母一直是研究异源淀粉样蛋白之间相互作用/交叉播种的优秀模型系统,更多是因为存在内源性酵母朊病毒。在这里,我们研究了非富含谷氨酰胺(非Q)的转甲状腺素蛋白与富含谷氨酰胺(Q)的酵母朊病毒蛋白Sup35之间的相互作用。我们在酵母中建立了工程化双突变体(F87M/L110M)M-TTR-GFP的聚集。与酵母中酸性pH下的野生型TTR-GFP相比,该突变体是单体的,并且容易形成聚集体。有趣的是,在Sup35的内源性朊病毒形式[]存在的情况下,M-TTR-GFP的聚集显著增强。[]的不同变体以不同效率接种M-TTR-GFP,并且在这些菌株中[]的治愈(失去朊病毒形式)减少了聚集。此外,与红色荧光蛋白(RFP)融合的Sup35朊病毒结构域的过表达也增加了M-TTR-GFP的聚集。M-TTR-GFP和NM-RFP聚集体共定位于液泡周围和近核区域。Sup35蛋白甚至在M-TTR-GFP聚集体中被免疫捕获。然而,M-TTR-GFP的过表达并未诱导Sup35聚集。因此,这两种淀粉样蛋白之间似乎是单向相互作用。然而,由于另一种酵母朊病毒[],未观察到对M-TTR-GFP聚集的影响。我们的研究结果因此显示了转甲状腺素蛋白与酵母朊病毒的分子相互作用,并支持序列相似性不是异源淀粉样蛋白相互作用的主要要求。