Delineating the Multifunctional Role of the Mouse Submandibular Gland Protein (mSMGP)

下颌下腺是哺乳动物的主要唾液腺。位于口腔底部下方，这个腺体产生接近三分之二的正常（未受刺激的）唾液分泌物。虽然唾液的消化和湿润功能对我们大多数人来说更为熟悉，但唾液中含有丰富的蛋白质，这些蛋白质执行着大量的生物功能。从老鼠到人类，这些功能在哺乳动物物种中是相似的，但并不完全相同。我们的实验室使用扫描技术（蛋白质组学）鉴定了大量由小鼠下颌腺分泌的蛋白质。我们对一种叫做mSMGP的蛋白质的功能特别感兴趣，以及它如何与我们已经确定的其他一些蛋白质相互作用。这些蛋白质相互作用是许多生物过程的基础，但我们目前对mSMGP的兴趣集中在我们最近的发现，它可以干扰口腔中的细菌，从而有助于唾液的一个可能鲜为人知的功能：防御微生物入侵。我们希望更全面地了解mSMGP的这些防御特性。它能杀死细菌还是仅仅抑制它们的生长？这种蛋白质的结构是什么使它对细菌有危险？唾液中是否需要其他蛋白质来帮助mSMGP执行这些防御任务？我们将采用的方法来回答这些问题，包括基因编辑方法，可以从小鼠中完全去除mSMGP。我们将通过将细菌暴露于我们的工程小鼠的唾液或改性的mSMGP溶液中，来观察当mSMGP缺失或其结构改变时会发生什么。我们还将使用增强的蛋白质组学技术来寻找可能与mSMGP相互作用的蛋白质。这些技术将包括在mSMGP上附加一个“标签”，这样就可以跟踪它与其他蛋白质的相互作用。我们将从这些研究中获得的知识与我们对人类中发现的这种蛋白质的了解进行比较。比较这两个物种的蛋白质在加拿大和国际舞台上的许多不同领域都是有用的。首先，它将帮助我们了解唾液和唾液蛋白在保护我们的身体免受微生物攻击方面的重要性。其次，它将帮助我们了解这种蛋白质的功能是如何在我们的进化史上被保存下来的。最后，它将支持健康研究，因为它将阐明使用动物系统作为人类疾病模型的有用性和局限性。

The submandibular gland is a major salivary gland in mammals. Located beneath the floor of the mouth, this gland produces close to two-thirds of normal (unstimulated) saliva secretions. While the digestive and humidifying functions of saliva are more familiar to most of us, saliva contains an abundance of proteins that carry out a huge range of biological functions. These functions are similar, but not identical, across mammalian species from mice to humans. Our lab has used scanning techniques (proteomics) to identify a large number of the proteins secreted by the submandibular gland in mice. We are particularly interested in the function of one protein in particular, called mSMGP, and how it might interact with some of the other proteins we have identified. These protein interactions are fundamental to many biological processes, but our current interest in mSMGP centres around our recent discovery that it can interfere with bacteria in the mouth, thus contributing to a perhaps lesser-known function of saliva: defence against microbial invasion. We are looking to understand these defensive properties of mSMGP more completely. Does it kill bacteria or simply inhibit their growth? What it is about this protein's structure that makes it dangerous to bacteria? Are other proteins in saliva required to help mSMGP carry out these defensive duties? The methods we will employ to answer these questions involve gene editing methods that can remove mSMGP from mice altogether. We will see what happens when mSMGP is absent, or when its structure is altered, by exposing bacteria to saliva from our engineered mice or to solutions of modified mSMGP. We will also use enhanced proteomic techniques to look for proteins that potentially interact with mSMGP. These techniques will involve attaching a "tag" to mSMGP so that its interactions with other proteins can be tracked. The knowledge we will gain from these studies will be compared to what we know about the version of this protein found in humans. Comparing the protein in these two species will be useful in many different fields, both in Canada and on the international stage. First, it will help us understand the importance of saliva and salivary proteins in defending our bodies against microbial attacks. Secondly, it will help us understand how the function of this protein has (or has not) been conserved over our evolutionary history. And finally, it will support health research because it will clarify both the usefulness and the limitations of using animal systems as models of human disease.