Signaling in Anergy: from Fyn to Ras and beyond

在外周T细胞中，与富含鞘糖脂的微结构域（PAG）相关的磷蛋白似乎通过将C-末端Src-激酶（Csk）募集到质膜上而起到细胞活化的负调节剂的作用。通过与PAG的结合，Csk能够抑制膜相关Src激酶p56 lck和p59 fyn的活性。在激活后，PAG被一种未鉴定的磷酸酶去磷酸化，其与Csk的结合丧失，允许随后激活Src激酶和诱导信号传导。该项目的目的是确定负责这种活性的磷酸酶，因为它是调节Src激酶活性的潜在靶点，从而调节T细胞的活性。PAG在T细胞发育、诱导无反应性、粘附和迁移中的作用也将被探索，因为这些是已知Src激酶参与的过程。此外，我们将进一步探索已知的蛋白质关联（即Csk，Fyn）和棕榈酰化在将PAG靶向GEM中的功能，同时还将寻找新的蛋白质，以帮助我们充分了解这种新型适配器的调节功能。我们将采用几种策略来观察这些相互作用的动态，特别是激活时发生的变化。最后，由于数据表明可能存在另一种PAG样分子，我们将鉴定这种蛋白质。

In peripheral T-cells, the phosphoprotein associated with glycosphingolipid-enriched microdomains (PAG) appears to function as a negative regulator of cellular activation by recruiting the C-terminal Src-kinase (Csk) to the plasma membrane. Via its association to PAG, Csk is able to inhibit the activity of the membrane-associated Src-kinases p56lck and p59fyn. Upon activation, PAG becomes dephosphorylated by an unidentified phosphatase and its association with Csk is lost, allowing for the subsequent activation of the Src-kinases and the induction of signaling. The aim of this project is to identify the phosphatase responsible for this activity, as it is a potential target for regulating the activity of Src-kinases and thereby regulating the activity of T-cells. The role of PAG in T-cell development, the induction of anergy, adhesion and migration shall also be explored, as these are processes in which Src-kinases are known to be involved. Additionally, we shall further explore the known protein associations (i.e. Csk, Fyn) and the function of palmitoylation in targeting PAG to the GEMs, while also looking for new proteins that may help us to fully understand the regulatory functions of this novel adaptor. We shall employ several strategies to observe the dynamics of these interactions, in particular the changes which occur upon activation. Finally, as data suggests that there may be another PAG-like molecule, we shall identify this protein.