Development of a general system for the production of controlled levels of proteins in eukaryotic cells

在高等生物细胞中表达特定设计蛋白质的能力是现代生物学和生物技术的重要工具。它被广泛用于生产医疗用途的新药和疫苗。最近的例子包括生产抗乳腺癌药物赫赛汀和抗人类乳头瘤病毒疫苗Gardisil，它们分别在哺乳动物和昆虫细胞中生产。作为旨在在植物中以低成本生产疫苗的研究方案的一部分，我们开发了一种非常有效的方法，可以在叶片中生产大量特定蛋白质。这种方法对于筛选不同蛋白质是否有能力开发成新疫苗非常有用，特别是因为这些蛋白质可以在几天内生产出来。此外，与同事们一起，我们已经能够证明我们可以使用该系统在植物中表达活性酶。这意味着我们可以改变植物的新陈代谢，使其产生可能用于工业或医学的新化合物。在目前的应用中，我们建议进一步开发表达蛋白质的系统，使其更容易被其他研究人员使用。我们的新系统的一大优点是可以控制每一种蛋白质的产量。当几种蛋白质一起工作时，这一点很重要，因为它们并不总是以相同的量存在。例如皮肤分泌的抗体；它们由四种不同的蛋白质组成，这些蛋白质在组装的复合物中以不同的数量存在。由于用现有的方法很难制造出这种抗体，因此受到了广泛的关注。另一个用途是引入一系列酶，这些酶可以在代谢途径中催化一系列反应。在这样的途径中，酶的含量往往相差很大——这一事实对于确保合成正确的化合物非常重要。因此，能够控制每种酶的水平将是非常重要的。虽然最初是作为植物体内快速生产蛋白质的一种手段而发展起来的，但最近的实验表明，我们的系统也可能在其他高等生物的昆虫细胞中工作得很好。我们希望检查这是否真的是真的，并测试在其他高等生物细胞中的表达。如果这些实验如我们预期的那样进行，这项研究将对药物和其他重要蛋白质的产生产生深远的影响。

The ability to express specifically designed proteins in the cells of higher organisms is a vital tool in modern biology and biotechnology. It is widely used to produce new medicines and vaccines for medical applications. Recent examples of this include the production of the anti-breast cancer drug, Herceptin, and the anti-human papilloma virus vaccine, Gardisil, which are produced in mammalian and insect cells, respectively. As part of a research programme aimed at producing vaccines at low cost in plants, we have developed a very efficient method for producing significant quantities of specific proteins in leaves. This method will be very useful for screening different proteins for their ability to be developed into new vaccines, especially since the proteins can be produced in only a few days. In addition, with colleagues, we have been able to show that we can use the system to express active enzymes in plants. This means we can alter the plant's metabolism so that it can produce new compounds which maybe of use to industry or medicine. In the current application, we propose to further develop our system for expressing proteins so that it can be more easily used by other researchers. A great advantage of our new system is that it is possible to control the amount of each protein that is produced. This is important when several proteins operate together since they are not always present in the same amount. Example of this are antibodies which are secreted by the skin; these consist of four different proteins which are present in different amounts in the assembled complex. Such antibodies have attracted much attention as therapies are very difficult to make by existing methods. Another use will be the introduction of a series of enzymes which can catalyse a series of reactions in a metabolic pathway. In such pathways, the enzymes are often present in very different amounts - a fact which is very important in ensuring that the correct compounds are made. Therefore being able to control the levels of each enzyme will be very important. Though originally developed as a means of the rapid production of proteins in plants, recent experiments have suggested that our system may also work well in insect cells of other higher organisms. We wish to examine if this is really true and to test expression in the cells of other higher organisms. If these experiments work as we expect, the research will have profound effects on how medicines and other important proteins are produced.