Heterologous aggregates promote de novo prion appearance via more than one mechanism.
Heterologous aggregates promote de novo prion appearance via more than one mechanism.
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DOI：
10.1371/journal.pgen.1004814
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发表时间：
2015-01
期刊：
影响因子：
4.5
通讯作者：
Liebman SW
中科院分区：
文献类型：
--
作者：
Arslan F;Hong JY;Kanneganti V;Park SK;Liebman SW
朊病毒是特定蛋白质的自我延续构象变体。在酵母中，朊病毒引起可遗传的表型特征。大多数已知的酵母朊病毒在其朊病毒结构域中含有富含谷氨酰胺 (Q)/天冬酰胺 (N) 的区域。 [PSI+]（Sup35 的朊病毒形式）在存在 [PIN+]（Rnq1 的朊病毒形式）的情况下，Sup35 短暂过量产生后，以显着增强的速率从头出现。在这里，我们建立了 Sup35 聚集体在与其他细胞蛋白相关的过度表达期间的时间从头外观。当在 [PIN+] 细胞中过表达时，荧光标记的 Sup35 最初会形成一个或几个点。其中一个点是液泡周围的，与聚集的 Rnq1 点共定位并生长成外围环/线，其中一些也与 Rnq1 共定位。不在液泡附近的 Sup35 点并不总是与 Rnq1 共定位，并且在环开始生长时消失。双分子荧光互补未能检测到[PSI +][PIN +]细胞中Sup35-VN和Rnq1-VC之间的任何相互作用。相比之下，所有 Sup35 聚集体，无论是新诱导的还是已建立的 [PSI +]，都与分子伴侣 Hsp104、Sis1、Ssa1 和真核释放因子 Sup45 完全共定位。在缺乏 [PIN+] 的情况下，过度表达的聚集蛋白（例如富含 Q/N 的 Pin4C 或富含 Q/N 的 Mod5）也可以促进 [PSI +] 的从头出现。与 Rnq1 类似，过表达的 Pin4C 与新出现的 Sup35 聚集体短暂共定位。然而，在缺乏 [PIN +] 的情况下，在 [PSI+] 诱导过程中未检测到 Mod5 和 Sup35 之间存在相互作用。虽然 Sup35 和 Rnq1 或 Pin4C 聚集体的共定位与异源聚集体交叉播种 [PSI +] 的从头出现的模型一致，但 Mod5 和 Sup35 之间缺乏相互作用留下了其他机制的可能性。我们还表明，在 [PIN +] 独立途径中，[PSI+] 聚集体的从头出现需要 Hsp104。某些蛋白质可能会错误折叠成富含 β-折叠的自播种聚集体。这些蛋白质似乎与朊病毒、阿尔茨海默病和帕金森病等神经退行性疾病有关。酵母朊病毒也会错误折叠成自播种聚集体，并为研究这些流氓聚合物如何首次出现提供了一个很好的模型。在异源朊病毒或朊病毒样聚集体存在的情况下，通过朊病毒蛋白的瞬时过度表达，可以在酵母中非常频繁地出现从头朊病毒。在这里，我们表明，一种新诱导的朊病毒的聚集体最初在液泡附近形成点状结构。然后这些点在细胞外围长成环，然后变成液泡周围的较小环，并成熟为整个细胞质中发现的特征性可遗传朊病毒小点。我们发现两种异源朊病毒/朊病毒样聚集体与新出现的朊病毒蛋白聚集体存在相当大的共定位，这与现有的朊病毒聚集体可以与异源朊病毒蛋白从头聚集交叉传播的流行模型一致。然而，我们未能发现另一种异源聚集蛋白与其刺激出现的新出现的朊病毒聚集体之间存在任何物理相互作用，这与交叉播种不一致。
Prions are self-perpetuating conformational variants of particular proteins. In yeast, prions cause heritable phenotypic traits. Most known yeast prions contain a glutamine (Q)/asparagine (N)-rich region in their prion domains. [PSI+], the prion form of Sup35, appears de novo at dramatically enhanced rates following transient overproduction of Sup35 in the presence of [PIN+], the prion form of Rnq1. Here, we establish the temporal de novo appearance of Sup35 aggregates during such overexpression in relation to other cellular proteins. Fluorescently-labeled Sup35 initially forms one or a few dots when overexpressed in [PIN+] cells. One of the dots is perivacuolar, colocalizes with the aggregated Rnq1 dot and grows into peripheral rings/lines, some of which also colocalize with Rnq1. Sup35 dots that are not near the vacuole do not always colocalize with Rnq1 and disappear by the time rings start to grow. Bimolecular fluorescence complementation failed to detect any interaction between Sup35-VN and Rnq1-VC in [PSI +][PIN +] cells. In contrast, all Sup35 aggregates, whether newly induced or in established [PSI +], completely colocalize with the molecular chaperones Hsp104, Sis1, Ssa1 and eukaryotic release factor Sup45. In the absence of [PIN+], overexpressed aggregating proteins such as the Q/N-rich Pin4C or the non-Q/N-rich Mod5 can also promote the de novo appearance of [PSI +]. Similar to Rnq1, overexpressed Pin4C transiently colocalizes with newly appearing Sup35 aggregates. However, no interaction was detected between Mod5 and Sup35 during [PSI+] induction in the absence of [PIN +]. While the colocalization of Sup35 and aggregates of Rnq1 or Pin4C are consistent with the model that the heterologous aggregates cross-seed the de novo appearance of [PSI +], the lack of interaction between Mod5 and Sup35 leaves open the possibility of other mechanisms. We also show that Hsp104 is required in the de novo appearance of [PSI+] aggregates in a [PIN +]-independent pathway. Certain proteins can misfold into β-sheet-rich, self-seeding aggregates. Such proteins appear to be associated with neurodegenerative diseases such as prion, Alzheimer's and Parkinson's. Yeast prions also misfold into self-seeding aggregates and provide a good model to study how these rogue polymers first appear. De novo prion appearance can be made very frequent in yeast by transient overexpression of the prion protein in the presence of heterologous prions or prion-like aggregates. Here, we show that the aggregates of one such newly induced prion are initially formed in a dot-like structure near the vacuole. These dots then grow into rings at the periphery of the cell prior to becoming smaller rings surrounding the vacuole and maturing into the characteristic heritable prion tiny dots found throughout the cytoplasm. We found considerable colocalization of two heterologous prion/prion-like aggregates with the newly appearing prion protein aggregates, which is consistent with the prevalent model that existing prion aggregates can cross-seed the de novo aggregation of a heterologous prion protein. However, we failed to find any physical interaction between another heterologous aggregating protein and the newly appearing prion aggregates it stimulated to appear, which is inconsistent with cross-seeding.
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影响因子：
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作者：
Choe, Young-Jun;Ryu, Yangkyun;Seok, Yeong-Jae
通讯作者：
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影响因子：
4.8
作者：
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通讯作者：
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影响因子：
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作者：
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通讯作者：
Chernoff, YO
影响因子：
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作者：
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通讯作者：
LIEBMAN, SW
影响因子：
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作者：
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通讯作者：
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