Discoidin domain receptor signalling: from crystal structures to mechanisms

我们想找出细胞表面的特殊传感器蛋白，称为DDRs，是如何将信号传递到细胞内的。这项研究很重要，因为人类错误的DDR信号可能会导致疾病，例如关节炎和癌症。为了开发针对DDRs的药物，有必要了解DDRs的结构和信号机制。我们的研究将有助于实现这一目标。DDR由三部分组成：一部分伸出细胞外，第二部分嵌入细胞膜，第三部分面向细胞内部。以前的研究已经证实，DDR可以感知到胶原的存在，而胶原是所有结缔组织的主要成分。这使得细胞能够对其环境做出反应。当胶原蛋白结合到DDR的外部时，内部部分变得活跃，并通知细胞胶原蛋白已经被识别。我们不知道在这个过程中会发生什么，但我们相信，当DDR与胶原蛋白反应时，它们会改变形状。我们将使用一系列实验技术来研究DDR如何与胶原结合，以及它们对胶原结合有何反应。胶原蛋白很难研究，因为它是一个非常大的分子。在我们的实验中，我们将使用胶原蛋白多肽，这是胶原蛋白的小合成片段。我们发现，一些胶原肽可以刺激DDR活性，而另一些胶原肽则阻断DDR活性。我们以前的实验揭示了DDR是如何识别刺激性胶原肽的。我们现在想看看封闭肽是如何被识别的。通过比较刺激性和阻断性多肽获得的DDR结构，我们希望更多地了解信号传递过程中发生的形状变化。我们之前的实验也揭示了DDRS的整个外部与自己配对形成了所谓的二聚体。我们将对DDR二聚体进行微小而精确的改变，并研究它们对信号传递的影响。通过结合许多这样的观察，我们可以构建DDR分子内参与通过细胞膜传输信号的区域的详细地图。最后，我们创建了一个非常有用的工具来研究DDR功能：一组针对DDR1的抗体(DDR1是人类的两个DDR之一)。抗体通常是由动物制造的，以抵御病原体，但通过给小鼠注射DDR1蛋白，我们已经能够获得与DDR1结合的抗体。其中一些抗体阻断了DDR1信号，而另一些抗体即使在没有胶原蛋白的情况下也能刺激这种活动。为了了解这些抗体如何影响DDR1的活性，我们想确定它们在DDR1分子上的结合位置。这些信息将补充我们的DDR1分子内功能重要区域的地图。我们还计划制造针对第二种人类DDR DDR2的抗体。我们的抗体将是非常有用的研究工具，可以与其他研究人员共享。它们也可以用于诊断或治疗目的，但此类试剂的开发必须在制药公司进行。

We want to find out how specialised sensor proteins on the cell surface, called DDRs, transmit a signal into the cell. This research is important because faulty DDR signalling in humans can cause disease, for example arthritis and cancer. In order to develop drugs that target the DDRs, it is necessary to know the structure and understand the signalling mechanism of the DDRs. Our research will contribute towards this aim. The DDRs are composed of three parts: one part sticks out of the cell, a second part is embedded in the cell membrane, and a third part faces the interior of the cell. Previous studies have established that the DDRs are sensing the presence of collagen, which is a major constituent of all connective tissues. This allows cells to react to their environment. When collagen binds to the exterior part of DDRs, the interior part becomes active and informs the cell that collagen has been recognised. We do not understand what happens during this process, but we believe that the DDRs change their shape when they react with collagen. We will use a range of experimental techniques to study how DDRs bind collagen and how they respond to collagen binding. Collagen is difficult to study because it is a very large molecule. In our experiments we will use collagen peptides, which are small synthetic fragments of collagen. We have found that some collagen peptides can stimulate DDR activity, whereas others block DDR activity. Our previous experiments have revealed how DDR recognises a stimulatory collagen peptide. We now want to see how a blocking peptide is recognised. By comparing the DDR structures obtained with stimulatory and blocking peptides, we hope to learn more about the shape changes that occur during signal transmission. Our previous experiments have also revealed that the whole exterior part of DDRs pairs with itself to form what is called a dimer. We will make small, precise changes in the DDR dimer and study their effects on signalling. By combining many such observations, we can construct a detailed map of the regions within the DDR molecule that are involved in transmitting a signal across the cell membrane. Finally, we have created a very useful tool for studying DDR function: a set of antibodies directed against DDR1 (DDR1 is one of the two DDRs in humans). Antibodies are normally made by animals as a defence against pathogens, but by injecting mice with DDR1 protein, we have been able to obtain antibodies that bind to DDR1. Some of these antibodies block DDR1 signalling, whereas others stimulate this activity even in the absence of collagen. In order to understand how these antibodies influence DDR1 activity, we want to determine where on the DDR1 molecule they bind. This information will complement our map of functionally important regions within the DDR1 molecule. We also plan to create antibodies against the second human DDR, DDR2. Our antibodies will be extremely useful research tools that can be shared with other researchers. They could also be used for diagnostic or therapeutic purposes, but the development of such reagents would have to be carried out in a pharmaceutical company.