Prion Aggregates Are Recruited to the Insoluble Protein Deposit (IPOD) via Myosin 2-Based Vesicular Transport
Prion Aggregates Are Recruited to the Insoluble Protein Deposit (IPOD) via Myosin 2-Based Vesicular Transport
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DOI：
10.1371/journal.pgen.1006324
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发表时间：
2016-09-01
期刊：
影响因子：
4.5
通讯作者：
Tyedmers, Jens
中科院分区：
文献类型：
--
作者：
Kumar, Rajesh;Nawroth, Peter P.;Tyedmers, Jens
淀粉样蛋白的聚集与几种神经退行性疾病有关。将错误折叠和聚集的蛋白质隔离到专门的沉积位点可以降低其潜在的有害特性。酵母显示出淀粉样蛋白聚集体的独特沉积位点，称为“不溶性蛋白存款（IPOD）"，但对底物募集到该位点的机制一无所知。IPOD直接位于噬菌体组装位点（PAS）附近，在该位点处细胞启动自噬和细胞质至液泡靶向（CVT）途径，该途径用于将前体肽酶递送至液泡。CVT底物向PAS的募集被认为是通过Atg 9囊泡上的囊泡运输发生的，并且需要完整的肌动蛋白细胞骨架和“SNAP（可溶性NSF附着蛋白）受体蛋白（SNARE）”蛋白功能。然而，这是未知的囊泡运输机制是如何连接到肌动蛋白细胞骨架。我们证明，招聘模型淀粉样蛋白PrD-GFP和CVT底物的蛋白酶-氨肽酶1（preApe 1）的IPOD或PAS，分别被干扰后，遗传损伤Myo 2为基础的肌动蛋白电缆运输和SNARE蛋白功能。而不是在各自的沉积位点处积累，两种底物通常在相同的点状结构中可逆地积累在一起。CVT囊泡运输机制的组分包括Atg 8和Atg 9以及Myo 2，其与关节积聚部分共定位。因此，我们提出了一个模型，其中囊泡，装载preApe 1或PrD-GFP，通过Myo 2马达蛋白分别被招募到原肌球蛋白包被的肌动蛋白电缆，用于递送到PAS和IPOD。我们讨论的沉积在IPOD是不是淀粉样蛋白聚集体的降解途径的一个集成的强制性的一部分，但更有可能存储多余的聚集体，直到下游降解途径有能力把他们解放后的HSP 104解聚机。
Aggregation of amyloidogenic proteins is associated with several neurodegenerative diseases. Sequestration of misfolded and aggregated proteins into specialized deposition sites may reduce their potentially detrimental properties. Yeast exhibits a distinct deposition site for amyloid aggregates termed "Insoluble PrOtein Deposit (IPOD)", but nothing is known about the mechanism of substrate recruitment to this site. The IPOD is located directly adjacent to the Phagophore Assembly Site (PAS) where the cell initiates autophagy and the Cytoplasm-to-Vacuole Targeting (CVT) pathway destined for delivery of precursor peptidases to the vacuole. Recruitment of CVT substrates to the PAS was proposed to occur via vesicular transport on Atg9 vesicles and requires an intact actin cytoskeleton and "SNAP (Soluble NSF Attachment Protein) Receptor Proteins (SNARE)" protein function. It is, however, unknown how this vesicular transport machinery is linked to the actin cytoskeleton. We demonstrate that recruitment of model amyloid PrD-GFP and the CVT substrate precursor-aminopeptidase 1 (preApe1) to the IPOD or PAS, respectively, is disturbed after genetic impairment of Myo2-based actin cable transport and SNARE protein function. Rather than accumulating at the respective deposition sites, both substrates reversibly accumulated often together in the same punctate structures. Components of the CVT vesicular transport machinery including Atg8 and Atg9 as well as Myo2 partially co-localized with the joint accumulations. Thus we propose a model where vesicles, loaded with preApe1 or PrD-GFP, are recruited to tropomyosin coated actin cables via the Myo2 motor protein for delivery to the PAS and IPOD, respectively. We discuss that deposition at the IPOD is not an integrated mandatory part of the degradation pathway for amyloid aggregates, but more likely stores excess aggregates until downstream degradation pathways have the capacity to turn them over after liberation by the Hsp104 disaggregation machinery.