Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health - AgeCap, University of Gothenburg, Gothenburg, Sweden.
Institute for Biomedicine, Sahlgrenska Academy, Centre for Ageing and Health - AgeCap, University of Gothenburg, Gothenburg, Sweden; Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden.
J Biol Chem. 2022 Nov;298(11):102476. doi: 10.1016/j.jbc.2022.102476. Epub 2022 Sep 9.
The accumulation of misfolded proteins is a hallmark of aging and many neurodegenerative diseases, making it important to understand how the cellular machinery recognizes and processes such proteins. A key question in this respect is whether misfolded proteins are handled in a similar way regardless of their genetic origin. To approach this question, we compared how three different misfolded proteins, guk1-7, gus1-3, and pro3-1, are handled by the cell. We show that all three are nontoxic, even though highly overexpressed, highlighting their usefulness in analyzing the cellular response to misfolding in the absence of severe stress. We found significant differences between the aggregation and disaggregation behavior of the misfolded proteins. Specifically, gus1-3 formed some aggregates that did not efficiently recruit the protein disaggregase Hsp104 and did not colocalize with the other misfolded reporter proteins. Strikingly, while all three misfolded proteins generally coaggregated and colocalized to specific sites in the cell, disaggregation was notably different; the rate of aggregate clearance of pro3-1 was faster than that of the other misfolded proteins, and its clearance rate was not hindered when pro3-1 colocalized with a slowly resolved misfolded protein. Finally, we observed using super-resolution light microscopy as well as immunogold labeling EM in which both showed an even distribution of the different misfolded proteins within an inclusion, suggesting that misfolding characteristics and remodeling, rather than spatial compartmentalization, allows for differential clearance of these misfolding reporters residing in the same inclusion. Taken together, our results highlight how properties of misfolded proteins can significantly affect processing.
蛋白质错误折叠的积累是衰老和许多神经退行性疾病的标志，因此了解细胞机制如何识别和处理这些蛋白质非常重要。在这方面的一个关键问题是，无论其遗传起源如何，错误折叠的蛋白质是否以相似的方式处理。为了研究这个问题，我们比较了三种不同的错误折叠蛋白，guk1-7、gus1-3 和 pro3-1，细胞如何处理它们。我们发现，尽管这三种蛋白都高度过表达，但它们都没有毒性，这突出了它们在分析细胞对错误折叠的反应时的有用性，而不会产生严重的应激。我们发现错误折叠蛋白的聚集和去聚集行为存在显著差异。具体来说，gus1-3 形成了一些聚集体，这些聚集体不能有效地招募蛋白去折叠酶 Hsp104，也不能与其他错误折叠报告蛋白共定位。引人注目的是，虽然这三种错误折叠蛋白通常都会共同聚集并共定位到细胞中的特定部位，但去聚集的情况却明显不同；pro3-1 聚集体的清除速度比其他错误折叠蛋白快，而且当 pro3-1 与缓慢解析的错误折叠蛋白共定位时，其清除速度不会受到阻碍。最后，我们使用超分辨率荧光显微镜和免疫金标记电镜观察到，这两种方法都显示不同错误折叠蛋白在包涵体内的均匀分布，这表明错误折叠的特征和重塑，而不是空间分隔，允许这些错误折叠报告蛋白在同一个包涵体内进行差异清除。总之，我们的结果强调了错误折叠蛋白的特性如何显著影响其处理。
