Molecular mechanisms underlying the S100A12-mediated activation of phagocytes: Interaction with cellular receptors and function as "damage associated molecular pattern" protein

粒细胞特异性蛋白S100 A12在炎症条件下过表达，并已被归因于促炎损伤相关分子模式分子（DAMP）的组。我们分析了S100 A12与模式识别受体（PRR）结合的特性。在我们先前资助的项目中，我们可以证明S100 A12的表达和释放在体外和体内通过炎症激发快速诱导。由于其他DAMP已被证明通过Toll样受体（TLR）发出信号，我们进行了表面等离子体共振研究，揭示了S100 A12与Toll样受体和TLR 4的结合。为了深入了解S100 A12的功能，我们现在将对S100 A12诱导的单核细胞反应进行全局基因表达分析，并将其与LPS诱导的基因表达谱进行比较，以深入了解确切的信号传导途径。我们将阐明参与S100 A12诱导的单核细胞活化的分子机制和不同PRR的相对贡献。在分别敲低或过表达TLR 4或TLR 4复合物后，细胞将用于体外实验。我们将使用β-/-小鼠和表达非功能性TLR 4的小鼠进行离体和体内研究。此外，计划建立过表达人S100 A12的转基因小鼠。

The granulocyte-specific protein S100A12 is overexpressed during inflammatory conditions and has been ascribed to the group of pro-inflammatory Damage Associated Molecular Pattern molecules (DAMPs). We have analyzed the characteristics of S100A12-binding to the pattern recognition receptor (PRR) RAGE (Receptor for Advanced Glycation End products). In our previously funded project we could demonstrate that S100A12 expression and release is rapidly induced in vitro and in vivo by inflammatory challenge. As other DAMPs have been shown to signal via Toll-like receptors (TLRs), we have performed surface plasmon resonance studies revealing binding of S100A12 to both RAGE and TLR4. To gain insight into the function of S100A12 we will now perform a global gene expression analysis of S100A12-induced responses of monocytes and compare this with LPS-induced gene expression profiles to get insights into the exact signalling pathways. We will elucidate the molecular mechanisms involved in the S100A12-induced activation of monocytes and the relative contribution of different PRRs. Cells will be used for in vitro-experiments after knock-down or overexpression of RAGE or the TLR4-complex, respectively. We will use RAGE-/- mice and also mice expressing a non-functional TLR4 for ex vivo and in vivo studies. In addition, a transgenic mouse over-expressing human S100A12 is planned.