Interdependence of Antimicrobial and Pro-inflammatory Activities Mediated byS100A12 in the Innate Immune Response

人类的先天免疫系统由几个组件组成，这些组件协同工作以抑制 发病机制。作为先天免疫系统的成熟成员，S100A12已知进行 锌离子封存的抗菌活性。这种隔离限制了病原体对锌离子的访问 对它们的繁殖至关重要的营养物质。此外，在感染过程中，S100A12与膜相互作用 受体，如晚期糖基化终产物受体(RAGE)，启动促炎 信号级联。虽然已知参与抗微生物和促炎活动，但 S100A12的相互作用方式，特别是与膜受体的相互作用方式尚不清楚。我们在这方面的目标 建议对S100A12的金属结合特性进行表征，使其具有抗菌性能 并对S100A12与RAGE的相互作用形成原子尺度的理解。我们建议这一点 相互作用是由其抗菌活动启动的，这使得我们可以假设，抗菌和促进剂- S100A12的炎症活性是相互依赖的。 我们的研究表明，S100A12通过锌离子的固存抗菌活性，经历了自我 导致低聚物形成的组装。我们还表明，这种自组装依赖于 S100A12的浓度。这些结果与文献中的报告一起展示了 在血清和人体组织中存在S100A12寡聚体，这使得我们能够提出一种方案 描述S100A12在免疫系统中的作用。该模型提出了S100A12浓度依赖关系 细胞中的促炎作用是由其抗菌反应启动的，从而建立了 其抗菌活性和促炎活性之间的相关性。为了检验我们的假设，我们提出了 以下具体目的是表征S100A12的抗菌功能及其寡聚体的作用：(I) S100A12齐聚物中过渡金属离子配位环境的表征；(Ii) 确定了S100A12齐聚的机理；以及(Iii)确定了S100A12齐聚的依赖性 S100A12与RAGE的相互作用方式和齐聚顺序。 这些拟议的研究将提供S100A12-RAGE的原子和分子水平的快照 体外相互作用，这将为这些细胞之间相互作用的模式提供指导 体内的成分。与我们的长期目标一致，即揭开金属依赖过程的原子化细节 在人类免疫反应中，这一提议将提供对金属依赖自我调节的作用的见解。 S100A12的装配。这些研究将增进对S100A12功能的理解，并提供 为设计新的疗法奠定了基础。

The human innate immune system is composed of several components that work in conjunction to curtail pathogenesis. As a well-established member of the innate immune system, S100A12 is known to conduct antimicrobial activities via sequestration of zinc ions. This sequestration limits the pathogen's access to Zn2+, a critical nutrient for their proliferation. Furthermore, during infection, S100A12 interacts with membrane receptors such as the receptor for advanced glycation end products (RAGE) to initiate a pro-inflammatory signaling cascade. Although known to participate in both antimicrobial and pro-inflammatory activities, the mode of interaction of S100A12, particularly with the membrane receptors, is not known. Our goal in this proposal is to characterize the metal binding properties of S100A12 that allow it to perform antimicrobial activities and develop an atomic scale understanding of interaction of S100A12 with RAGE. We propose that this interaction is initiated by its antimicrobial activities allowing us to hypothesize that the antimicrobial and pro- inflammatory activities of S100A12 are interdependent. Our studies demonstrate that by the antimicrobial activity of Zn2+ sequestration, S100A12 undergoes self- assembly leading to the formation of oligomers. We also show that this self-assembly is dependent on the concentration of S100A12. These results, in conjunction with reports in the literature demonstrating the presence of oligomeric S100A12 species in blood serum and human tissues, have allowed us to propose a scheme describing the role of S100A12 in the immune system. This model proposes S100A12 concentration dependent pro-inflammatory actions in cells that are initiated upon its antimicrobial responses, thereby establishing a correlation between its antimicrobial and pro-inflammatory activities. To test our hypothesis, we propose the following specific aims to characterize S100A12 antimicrobial functions and the role of its oligomers: (i) characterization of the coordination environment of transition metal ions in oligomeric S100A12 assemblies; (ii) identification of the mechanism of oligomerization of S100A12; and (iii) determination of the dependence of the mode of interaction of S100A12 with RAGE and the order of oligomerization. These proposed studies will provide atomic- and molecular-level snapshots of the S100A12-RAGE interactions in vitro, which will provide guidance for the mode of the interaction between these cellular components in vivo. In line with our long-term goal to unravel atomistic details of metal-dependent processes in the human immune response, this proposal will provide insights into the role of metal dependent self- assembly of S100A12. These studies will enhance the understanding of the functioning of S100A12 and provide basis for the design of novel therapeutics.