Essential genetic interactors of SIR2 required for spatial sequestration and asymmetrical inheritance of protein aggregates.
Essential genetic interactors of SIR2 required for spatial sequestration and asymmetrical inheritance of protein aggregates.
复制标题
DOI：
10.1371/journal.pgen.1004539
复制
发表时间：
2014-07
期刊：
影响因子：
4.5
通讯作者：
Nyström T
中科院分区：
文献类型：
--
作者：
Song J;Yang Q;Yang J;Larsson L;Hao X;Zhu X;Malmgren-Hill S;Cvijovic M;Fernandez-Rodriguez J;Grantham J;Gustafsson CM;Liu B;Nyström T
Sir2是酵母衰老的中心调节因子，它的缺失增加了应激和衰老诱导的错误折叠蛋白沉积在聚集体和包涵体中的子代细胞遗传。在这里，通过以被动的方式量化预测会影响聚集遗传的性状，我们发现被动扩散模型不能解释Sir2依赖的母亲偏向分离的失败，无论是由错误折叠的Huntingtin，Htt103Q，疾病蛋白形成的小聚集，还是热诱导的Hsp104相关聚集。相反，我们发现Sir2的遗传相互作用网络包含母亲偏向分离所需的特定必需基因，包括编码肌动蛋白细胞骨架组件的基因、与肌球蛋白V相关的肌球蛋白V马达蛋白Myo2和肌动蛋白组织蛋白Cmd1。与Hsp104-GFP共染色表明，错误折叠的Htt103Q被隔离在小聚集体中，类似于热应激形成的应力焦点，无法结合成包涵体。重要的是，这些Htt103Q焦点，以及先前被证明是稳定的应力焦点的ATPase缺陷的Hsp104Y662a相关结构，与Cmd1和Myo2富含结构共同定位，超分辨三维显微镜显示它们与肌动蛋白缆线相关。此外，我们还发现Hsp42是形成热诱导Hsp104Y662A型焦点所必需的，而不是Htt103Q所必需的，这表明形成Hsp104Y662A型焦点的途径并不相同。除了参与肌动蛋白依赖过程的基因外，Htt103Q不对称遗传所需的Sir2相互作用物和热诱导的聚集体还编码参与ER到高尔基体运输/ER动态平衡的必要SEC基因。不对称的细胞分裂是细胞再生的关键，萌芽酵母利用这种胞质分裂模式，从母细胞产生年轻的子细胞，随着每次分裂逐渐变老。因此，在分裂过程中，后代的年龄相貌被重置，这一现象需要对细胞质的“老化因素”，包括受损/聚集的蛋白质，进行偏向的分离。关于聚集的蛋白质如何以母细胞偏向的方式进行分离，有两种模型；一种认为不对称遗传纯粹是聚集体随机但缓慢扩散的被动结果，而另一种模型的原因是特定的因素/细胞器阻止聚集体自由扩散到子细胞中。在目前的工作中，我们通过量化预测的通过被动扩散影响遗传的性状，并确定与Sir2相互作用的基本基因之间的非对称遗传所需的因素，测试了被动扩散模型或因素依赖模型在解释非对称遗传中似乎最相关。Sir2是以前被证明是母亲偏向分离所必需的基因。我们表明，聚集体的被动扩散不足以建立母亲偏向的分离，内质网到高尔基体的运输，除了肌动蛋白细胞骨架、钙调蛋白和Myo2马达蛋白外，是限制热应激诱导的聚集体和亨廷顿病蛋白Htt103Q形成的聚集体遗传的关键成分。
Sir2 is a central regulator of yeast aging and its deficiency increases daughter cell inheritance of stress- and aging-induced misfolded proteins deposited in aggregates and inclusion bodies. Here, by quantifying traits predicted to affect aggregate inheritance in a passive manner, we found that a passive diffusion model cannot explain Sir2-dependent failures in mother-biased segregation of either the small aggregates formed by the misfolded Huntingtin, Htt103Q, disease protein or heat-induced Hsp104-associated aggregates. Instead, we found that the genetic interaction network of SIR2 comprises specific essential genes required for mother-biased segregation including those encoding components of the actin cytoskeleton, the actin-associated myosin V motor protein Myo2, and the actin organization protein calmodulin, Cmd1. Co-staining with Hsp104-GFP demonstrated that misfolded Htt103Q is sequestered into small aggregates, akin to stress foci formed upon heat stress, that fail to coalesce into inclusion bodies. Importantly, these Htt103Q foci, as well as the ATPase-defective Hsp104Y662A-associated structures previously shown to be stable stress foci, co-localized with Cmd1 and Myo2-enriched structures and super-resolution 3-D microscopy demonstrated that they are associated with actin cables. Moreover, we found that Hsp42 is required for formation of heat-induced Hsp104Y662A foci but not Htt103Q foci suggesting that the routes employed for foci formation are not identical. In addition to genes involved in actin-dependent processes, SIR2-interactors required for asymmetrical inheritance of Htt103Q and heat-induced aggregates encode essential sec genes involved in ER-to-Golgi trafficking/ER homeostasis. Asymmetric cell division is key to cellular rejuvenation and budding yeast exploits this mode of cytokinesis to generate a young daughter cell from a mother cell that with each division grows progressively older. Thus, age physiognomies are reset in the progeny during division, a phenomenon that requires a mother-biased segregation of cytoplasmic ‘aging factors’, including damaged/aggregated proteins. There are two models for how aggregated proteins are segregating in a mother cell-biased fashion; one holds that asymmetric inheritance is a purely passive outcome of the aggregates' random but slow diffusion whereas the other model reasons that specific factors/organelles prevent free diffusion of aggregates into the daughter cell. In the present work, we tested whether the passive diffusion model or the factor-dependent model appear most relevant in explaining asymmetrical inheritance by quantifying traits predicted to affect inheritance by passive diffusion and identifying factors required for asymmetrical inheritance amongst essential genes interacting with SIR2; a gene shown previously to be required for mother-biased segregation. We show that passive diffusion of aggregates is not sufficient to establish mother-biased segregation and that ER to Golgi trafficking, in addition to the actin cytoskeleton, calmodulin, and the Myo2 motor protein, are key components restricting the inheritance of both heat stressed-induced aggregates and aggregates formed of the Huntington disease protein Htt103Q.
登录
查看更多内容
影响因子：
9.2
作者：
Higuchi, Ryo;Vevea, Jason D.;Swayne, Theresa C.;Chojnowski, Robert;Hill, Vanessa;Boldogh, Istvan R.;Pon, Liza A.
通讯作者：
Pon, Liza A.
影响因子：
3.7
作者：
Büttner S;Delay C;Franssens V;Bammens T;Ruli D;Zaunschirm S;de Oliveira RM;Outeiro TF;Madeo F;Buée L;Galas MC;Winderickx J
通讯作者：
Winderickx J
影响因子：
3.3
作者：
Ho, J;Bretscher, A
通讯作者：
Bretscher, A
DOI：
10.1083/jcb.200304030
发表时间：
2003-12-22
期刊：
The Journal of cell biology
影响因子：
--
作者：
Estrada P;Kim J;Coleman J;Walker L;Dunn B;Takizawa P;Novick P;Ferro-Novick S
通讯作者：
Ferro-Novick S
DOI：
10.1073/pnas.0804550105
发表时间：
2008-12-02
影响因子：
11.1
作者：
Erjavec, N.;Cvijovic, M.;Nystrom, T.
通讯作者：
Nystrom, T.