Amyloids and Oligomers. Curvilinear and annular structures and their interaction with exosomes and whole cells

背景：有许多蛋白质聚集在一起形成有序的淀粉样蛋白。淀粉样蛋白在酵母和细菌中具有功能性作用。它们也是潜在的新型纳米材料。此外，蛋白质（如朊病毒蛋白）的错误折叠和自组装与包括疯牛病（BSE）和羊瘙痒症在内的疾病有关。而淀粉样β蛋白（Ab）与人类阿尔茨海默病有关，除了长而不分支的纤维外，还经常形成特定的前纤维组装体。这些包括环形（甜甜圈）形状的结构以及更多的曲线原纤维。这些前原纤维结构通常对脂质双层具有高亲和力，它们与脂质膜的相互作用可以破坏细胞过程和平衡;这会导致一系列事件，最终导致细胞死亡。Ab-聚集体通过细胞膜的“地毯”破坏细胞完整性，或通过形成跨越细胞壁的小通道，从而导致钙离子不受控制地流入细胞，从而对细胞有毒。了解这些过程是揭示Ab引起细胞毒性的机制的关键。目前，这些相互作用的高分辨率分子成像，在天然的条件下，已受到限制，而离子通道测量已集中在重建的人工脂质双层，这很差的近似行为的抗体通道形成细胞膜。目的：-我们想研究抗体与脂质膜相互作用的基本过程。在低温条件下使用强大的电子显微镜，我们将图像的环形（甜甜圈）结构，形成跨脂质膜的通道。使用冷冻电子断层扫描，我们将获得三维分子的细节抗体地毯的细胞衍生膜表面在接近天然条件下。此外，我们的目标是探索机制的细节Ab 42离子通道形成细胞膜电生理学方法。我们将确定通常在具有不同Ab制剂的神经元上形成的Ab通道的大小和数量。通过这种方式，我们将揭示Ab 42离子通道在生理相关条件下对细胞过程的可能影响。我们将探讨Ab通道形成的细胞外和细胞内的膜面对的神经元。意义：-前纤维组装的结构将告知更广泛的淀粉样蛋白领域。我们希望这项研究将使我们更深入地了解不同的抗体组装如何影响细胞活力。这些研究将为更广泛的淀粉样蛋白领域提供信息。我们希望我们的研究能够突出Ab在痴呆早期破坏膜完整性方面的关键作用。我们的专家团队能够很好地研究这些基本的相互作用。

Background:- There are a number of proteins that clump together to form ordered fibrillary assembles known as amyloids. Amyloids can have functional roles in yeast and bacteria. They also represent potential novel nanomaterials. Furthermore, misfolding and self-assembly of proteins, such as the prion protein, are link with diseases including, mad-cow disease (BSE) and scrapie in sheep. While amyloid beta protein (Ab) is linked to Alzheimer's in humans.In addition to long unbranched fibrils, specific pre-fibrillary assemblies are often formed. These include annular (donut-ring) shaped structures as well as more curvilinear protofibrils. These prefibrillar structures often have a high affinity for lipid bilayers, their interaction with the lipid membrane can disrupt cellular processes and balance; this causes a cascade of events culminating in cell death. Ab-aggregates are toxic to cells by disrupting cell integrity through the 'carpeting' of the cell membrane, or via the formation of small channels that span the cell-wall, thereby causing an uncontrolled flow of calcium ions into the cell. Understanding these processes is key to uncovering the mechanism by which Ab causes cell toxicity. At present, high resolution molecular imaging of these interactions, in native-like conditions, has been limited, while ion channel measurements have focused on reconstituted artificial lipid bilayers, which poorly approximate the behaviour of Ab channel formation in cellular membranes. Aims:- We want to investigate the fundamental process of Ab interactions with lipid membranes. Using powerful electron microscopes under cryogenic conditions we will image the annular (donut-ring) structures that form channels across lipid membranes. Using cryo-electron tomography, we will obtain three-dimensional molecular details of Ab carpeting the cell derived membrane surface under near native conditions. Furthermore, we aim to probe the mechanistic details of Ab42 ion-channel formation in cellular membranes using electrophysiology methods. We will determine the size and number of Ab channels that typically form on a neuron with different Ab preparations. In this way we will uncover the likely effects that Ab42 ion channels have on cellular processes under physiologically relevant conditions. We will explore Ab channel formation on both the extra- and intra-cellular membrane face of neurons. Significance:- The structures of prefibrillar assemblies will inform the wider amyloid field. We hope this study will give us a deeper understanding of how different Ab assemblies impact cell viability. These studies will inform the wider amyloid field. We expect our studies to highlight the key role of Ab in disrupting membrane integrity in the early stages of dementia. Our team of experts is well placed to investigate these fundamental interactions.