Structural Analysis of {T}-Cell Signaling

While the structural analysis of metabolic networks is a well-established field, similar approaches have been scarcely applied to signaling networks. The shortage of such analyses could be mainly due to two reasons: On one side, the absence of enough information about signaling networks. On the other side, the intrinsic dynamic behavior of signaling processes limits the applicability of steady-state-based methods, which have proved to be successful for metabolic networks. In this contribution, we analyze the transfer of structural methods from metabolic networks to signaling processes. We show that, if the network is correctly formulated, concepts such us elementary flux modes are meaningful for signaling networks. Additionally, interesting non-intuitive properties of the networks, such as feedbacks or possible connections between proteins can be elucidated. We illustrate our methods on T-Cell Signaling. The activation of T-cells has to be exquisitely regulated since not only a decrease but also an increase can be very dangerous and lead to different diseases. Hence, T-cells have an extremely complex signaling machinery which assures that their activation only takes place where and when it should. We show that these methods can help to prove the consistency of the network and to discover key elements