Studies on histidine phosphorylation in Wnt/beta-catenin signaling

蛋白质中的氨基酸组氨酸可以通过磷酸化来修饰，从而改变这些蛋白质的功能，如文献中的几个例子所示。然而，到目前为止，只有少数几项研究涉及哺乳动物细胞的这种修饰。最新一代的抗体专门检测蛋白质中的磷酸组氨酸，现在可以更全面地分析组氨酸磷酸化在细胞过程中的功能。在我们的初步工作中，我们发现了组氨酸磷酸化在Wnt/β-catenin信号通路调节中的作用的证据。这一途径参与了许多生物学过程，包括细胞增殖、干细胞发育和分化，以及癌症等病理过程。WNT因子与特定的细胞表面受体结合，从而激活细胞质蛋白，如Dvl2，以增加β-连环蛋白的稳定性，从而改变基因转录。我们发现，组氨酸激酶和磷酸酶分别抑制和刺激Wnt信号，并且Dvl2蛋白被严重的组氨酸磷酸化。我们建议的目的是利用分子和细胞生物学方法破译Wnt信号中组氨酸磷酸化的相关性。特别是，我们将重点研究组氨酸磷酸化对Dvl2活性的影响，以及作为这一过程一部分的激酶和磷酸酶的作用，以及Wnt信号对组氨酸磷酸化的调节。此外，我们将把我们的分析扩展到检测和功能分析该途径的其他关键成分的组氨酸磷酸化。组氨酸磷酸化是一个相对较新的研究领域，据我们所知，以前没有人将其应用于Wnt信号转导，有望为这一生物和医学上高度相关的途径的功能和调控提供新的线索。

The amino acid histidine can be modified in proteins by phosphorylation which alters the function of these protein as has been shown for a few examples in the literature. However, until now only a few studies have addressed this modification in mammalian cells. The recent generation of antibodies that specifically detect phospho-histidines in proteins now allows a more general analysis of the function of histidine phosphorylation in cellular processes. In our preliminary work we have found evidence for a role of histidine phosphorylation in the regulation of the Wnt/beta-catenin signaling pathway. This pathway takes part in numerous biological processes, including cell proliferation, stem cell development and differentiation as well as in pathological processes such as cancer. Wnt factors bind to specific cell surface receptors thereby activating cytoplasmic proteins such as Dvl2 to increase the stability of the beta-catenin protein which alters gene transcription. We found that histidine kinases and phosphatases inhibit and stimulate Wnt signaling, respectively, and that the Dvl2 protein is heavily histidine phosphorylated. The aim of our proposal is to decipher the relevance of histidine phosphorylation in Wnt signaling using molecular and cell biological methods. In particular we will focus on the consequences of histidine phosphorylation for Dvl2 activity, on the role of of the kinases and phosphatases that are part of this process, as well as the regulation of histidine phosphorylation by Wnt signaling. Moreover we will extend our analysis to detect and functionally analyze histidine phosphorylation of other key components of the pathway. Histidine phosphorylation is a relatively new research field which has to our knowledge not been applied to Wnt signaling before and hopefully will yield new clues on the function and regulation of this biologically and medically highly relevant pathway.