SAGEs: Self-assembled peptide-based cages for the presentation, encapsulation and delivery of bioactive molecules to cells in culture

研究背景：在实验室或体内将生物活性分子（药物、DNA和蛋白质）输送到特定细胞的能力将对生物学和医学的许多分支产生影响。想象一下，能够选择性地发现并摧毁患病细胞；还是“简单地”在动物和人体试验之前在一系列细胞内测试新药的有效性？不幸的是，对于在细胞内传递生物活性分子的问题，目前还没有通用的解决方案，甚至定制的真正解决方案也很少。这个问题并不简单，最好的说明是生物学是如何进化出病毒来做到这一点的。病毒是令人惊讶的天然纳米级包裹，通常被称为病毒粒子。尽管病毒粒子有多种类型，但它们都有三个功能：(1)它们通常识别特定的细胞类型，它们通过在表面呈现分子来识别目标细胞上的分子；(2)穿透细胞外屏障；(3)它们传递有效载荷，即在宿主细胞中制造更多病毒的遗传信息。功能(1)和(2)由病毒外壳或衣壳执行。毫不奇怪，许多人试图模仿这些结构来传递RNA和DNA以外的有效载荷。研究的目的、目标和抱负：这项拟议工作的总体目标是制造出直径约为人类头发宽度百分之一的空心笼状颗粒，即所谓的SAGE颗粒。我们将以模块化的方式来做这件事，使用被称为肽的小版本蛋白质。每个肽模块将具有特定的功能来模拟病毒粒子的一种特性：一组将用于识别特定的细胞类型；另一个将用于构建粒子的外壳；第三组将携带具有生物活性的有效载荷。就其本身而言，这些模块根本没有用。然而，如果正确组合，它们可以组装成类似病毒的颗粒，但没有（致命的）RNA和DNA货物，相反，它们将含有药物或有用的蛋白质。为此，我们将建立一个由化学家、生物化学家、细胞生物学家和分子建模师组成的多学科团队，他们已经交付了SAGE颗粒。物理学家将共同设计和制造分子组装，然后与生物学家合作测试和可视化它们如何与细胞相互作用并传递有效载荷。潜在的应用和好处：在整个研究过程中，我们将与Syntaxin公司合作，该公司对靶向和杀死体内特定的病变细胞类型感兴趣。除了提供试剂和技术外，这种伙伴关系还将鼓励实际应用，从而为我们的研究提供明确和实用的终点。通过这种方式，我们将探索SAGE组装和工程的基础，以及功能性SAGE在细胞生物学和医学中的潜在应用。广义地说，这种构建复杂生物分子、组件和系统的模块化和系统化方法被称为“合成生物学”。合成生物学的目标和精神是使生物系统的工程更容易（即系统、快速和可预测），并最终制造有用的功能和产品。例如，合成生物学正在被认为对生产新药、生物燃料和精细化学品越来越重要。它由政府和研究委员会投资，目的是充分发展该领域，为英国（生物技术）工业和经济带来直接利益。我们的建议的一个关键方面是它符合这种精神和这些愿望：我们的目标是为上述三个属性中的每个属性制作一个不同模块的工具包；通过这种方式，模块可以快速、可靠地组合在一起，并产生可预测的结果，以产生针对和治疗不同细胞和疾病的不同颗粒。

CONTEXT OF THE RESEARCH: An ability to deliver biologically active molecules (drugs, DNA and proteins) to specified cells either in the lab or the body would impact on many branches of biology and medicine. Imagine being able to selectively find and destroy diseased cells; or "simply" to test the effectiveness of a new drug inside a range of cells before animal and human trials? Unfortunately, there is no general solution to this problem of delivering bioactive molecules within cells, and even bespoke true solutions are few and far between. The problem is not straightforward, and is best illustrated by how biology has evolved viruses to do this.Viruses are astonishing natural nanoscale packages, usually termed virions. Though they come in many types, all virions perform three functions: (1) they recognise often specific cell types, which they do by presenting molecules on their surfaces to recognize molecules on the target cells; (2) they penetrate the outer barriers of the cell; and (3) they deliver a payload, which is the genetic information to make more virus in the host cell. Functions (1) and (2) are performed by the viral coats, or capsids. Not surprisingly, many people have tried to mimic these structures to deliver payloads other than RNA and DNA. AIMS, OBJECTIVES AND ASPIRATIONS OF THE RESEARCH: The overall ambition of the proposed work is to produce hollow, cage-like particles that have the diameter of about one hundredth the width of a human hair, so-called SAGE particles. We will do this in a modular way, using small versions of proteins called peptides. Each peptide module will have a specific function to mimic one the properties of virions: one set will be made to recognize specific cell types; another will be used to construct the casing of the particles; and the third set will carry the biologically active payloads. On their own, these modules would not be useful at all. However, if combined correctly they could assemble into virus-like particles, but without the (deadly) RNA and DNA cargo, instead they would contain drugs or useful proteins.To do this we will build on a multidisciplinary team of chemists, biochemists, cell biologists and molecular modellers that has delivered the SAGE particles. The physical scientists will work together to design and make the assemblies of molecules, and then work with the biologists to test and visualise how they interact with cells and deliver their payloads.POTENTIAL APPLICATIONS AND BENEFITS: Throughout the research, we will work with a company, Syntaxin, interested in targeting and killing particular diseased cell types in the body. As well as providing reagents and know-how, this partnership will encourage real-life applications, and thus clear and practical end points for our research. In this way, we will explore both the fundamentals of SAGE assembly and engineering, and potential applications of functional SAGEs in cell biology and medicine.Broadly speaking, this modular and systematic approach to constructing complex biological molecules, assemblies and systems is called "synthetic biology". The aim and spirit of synthetic biology is to make the engineering of biological systems easier (that is, systematic, quick, and predictable) and ultimately to make useful functions and products. For example, synthetic biology is being recognised as increasingly important to generate new medicines, biofuels and fine chemicals. It is being invested in by Government and Research Councils, with the aim of developing the field sufficiently to be of direct benefit to the UK (biotech) industry and economy. One of the key aspects of our proposal is that it fits with this spirit and these aspirations: we aim to make a toolkit of different modules for each of the above three properties; in this way, modules could be combined rapidly, reliably and with predictable outcomes to generate different particles for targeting and tackling different cells and diseases.