Regulation of the proteasome by Fbxo7

活细胞主要由多种不同的蛋白质组成，每种蛋白质都有各自的功能和特性。就像任何人造机器的部件一样，这些蛋白质很容易“磨损”，并可能随着时间的推移而受损。一个细胞的健康，以及它所属的整个有机体的健康，取决于及时和具体地去除受损的蛋白质，以防止它们在有毒的聚集体中积聚，最终使细胞中毒。细胞已经进化出一种识别并摧毁不需要的蛋白质的机制，称为“泛素-蛋白酶体系统”。受损的蛋白质被标记上一连串的小泛素分子，将它们定位到细胞的“回收箱”--蛋白酶体。该系统未能清除蛋白质聚集体与多种人类疾病有关，包括帕金森氏病、阿尔茨海默病、II型糖尿病，还与那些涉及普恩蛋白的疾病有关，这些蛋白质导致人类的克雅氏病、牛的疯牛病和绵羊和山羊的瘙痒病。相反，泛素-蛋白酶体系统的过度活动与各种肌肉萎缩疾病有关，因此很明显，为了维持健康，需要对该系统进行适当的调节。最近，一项详细描述了蛋白酶体运行速度的控制器的特性的研究已经发表。这种名为PI31的蛋白质已被证明在不同的环境下既能增强蛋白酶体活性，又能降低蛋白酶体活性。然而，PI31并不是单独行动的。我们已经确定了一种名为Fbxo7的蛋白质，它不仅能够标记泛素破坏的蛋白质，而且还能与PI31结合。对果蝇的研究表明，这种相互作用增强了PI31调节蛋白酶体的能力，而缺乏被称为胡桃夹子的Fbxo7蛋白的果蝇会降低蛋白酶体的活性，导致雄性果蝇不育。我们发现，老鼠体内Fbxo7基因的缺失也会影响它们的生育能力。此外，人类Fbxo7基因的突变也与帕金森病有关，这表明Fbxo7也可能与PI31协同调节哺乳动物系统中的蛋白酶体活性。我们想要详细了解Fbxo7如何参与哺乳动物细胞中蛋白酶体活性的调节。我们将使用多种方法来研究PI31和Fbxo7之间的关系，确定这两种蛋白质之间的相互作用是否分别影响它们调节蛋白酶体活性和标记蛋白质降解的能力。我们还将通过在细胞系和小鼠模型中的一系列分析来确定Fbxo7在细胞中的缺失或过表达如何影响细胞中的蛋白酶体活性。通过做实验来扩大我们对蛋白质降解机制的理解，我们希望能够在临床相关的环境中影响并最终指导这些过程。

Living cells are largely constructed from a multitude of different proteins, each with their own individual functions and properties. Just like the components of any man-made machine, these proteins are susceptible to "wear and tear" and can become damaged over time. The health of a cell, and consequently the whole organism to which it belongs depends on the timely and specific removal of damaged proteins to prevent their accumulation in toxic aggregates that will eventually poison the cell. Cells have evolved a mechanism to identify and then destroy unwanted proteins, called the "ubiquitin-proteasome system". Damaged proteins are marked with chains of small ubiquitin molecules, targeting them to the proteasomes, the cell's "recycling bins". The failure of this system to clear protein aggregates has been linked to multiple human diseases, including Parkinson's disease, Alzheimer's disease, type II diabetes and is also implicated in those involving prion proteins which cause Creutzfeldt-Jakob disease in humans, BSE in cattle and scrapie in sheep and goats. Conversely, over-activity of the ubiquitin-proteasome system has been linked with various muscle atrophy diseases, it is therefore clear that proper regulation of this system is required for the maintenance of health.Recently, a study detailing the properties of a controller of the rate at which the proteasomes operate has been published. This protein, called PI31, has been shown to both increase and decrease proteasome activity under different circumstances. However, PI31 does not act alone. We have identified a protein called Fbxo7 that is not only capable of marking proteins for destruction with ubiquitin but which also binds to PI31. Studies in fruit flies have shown that this interaction enhances the ability of PI31 to regulate the proteasomes, and flies lacking their analgous Fbxo7 protein, which is called nutcracker, have reduced proteasome activity, and causes sterility in male flies. We have found that loss of the Fbxo7 in mice also affects their fertility. Furthermore, mutations in the human Fbxo7 gene have also been linked to Parkinson's disease, suggesting that Fbxo7 may also cooperate with PI31 to regulate proteasome activity in mammalian systems.We want to understand in detail how Fbxo7 participates in the regulation of proteasome activity in mammalian cells. We will use a variety of methods to investigate the relationship between PI31 and Fbxo7, determining whether the interaction between these two proteins affects their ability to regulate proteasome activity and mark proteins for degradation, respectively. We will also determine how the loss or over-representation of Fbxo7 in cells affects proteasome activity in cells using a range of assays both in cell lines and in an mouse model. By doing experiments to broaden our understanding of the protein degradation machinery, we hope to be able to affect and ultimately direct these processes in clinically relevant settings.