Report
Teaser, summary, work performed and final results
Periodic Reporting for period 1 - Cytokine Signalosome (Mapping Cytokine Signalling Networks using Engineered Surrogate Ligands)
Teaser
Cells use an intricate network of intracellular signaling molecules to translate environmental changes, sensed via surface receptors, into cellular responses. Despite the prominent role that these networks play in life itself, we still lack a comprehensive understanding of how...
Summary
Cells use an intricate network of intracellular signaling molecules to translate environmental changes, sensed via surface receptors, into cellular responses. Despite the prominent role that these networks play in life itself, we still lack a comprehensive understanding of how extracellular information is conveyed through them into specific bioactivities and fate decisions. In order to rationally manipulate cell fate, which could fundamentally change the way that we currently treat human diseases, first we need a systematic understanding of how signaling is initiated and propagated inside the cell. My primary research interest is to understand the cellular and molecular determinants of signaling specificity by cell surface receptors.
To address this important question, we use cytokines as a model system. Cytokines are a large family of secreted ligands that control every aspect of the mammalian physiology. They act as the major source of mid- and long-distance communication between cells, ensuring the coordinated response between different cell subsets. A clear example of this can be found in their regulation of the immune response. Cytokines critically contribute to initiate, maintain and define the type of immune response generated upon an external harm, thus making them highly relevant to human health. Indeed, cytokines are often found dysregulated in many human disorders including inflammation, cancer and auto-immunity. Despite their high clinical value, very few cytokines are used in the clinic, due to the high toxicity associated with their use. A better understanding of the molecular bases for cytokine-induced signaling and activities, could help us to design more efficient and less toxic therapies.
This program aims to tackle two important questions/objectives. The first one focuses on understanding the molecular bases defining signal activation by cytokines. The second one aims at use the information generated from objective 1 to engineer cytokine variants with a more defined set of biological responses. The primary research interest of the project is IL-6, a well-studied cytokine that plays a crucial role in immune regulation by controlling the intensity and duration of the inflammatory response. The information generated from these objectives will provide us with new insight into how cytokines elicit such complex biological responses, which in turn will allow us to design more targeted therapies with reduce toxicities.
Work performed
In the eighteen months since the project started we have advanced significantly in the development of the objectives described in this program. For objective one, we have stablished a cellular system in the lab where to study IL-6 responses in human T cells. Using purified CD4 T cells, we have performed a detail characterization of the signaling networks engaged by IL-6 in these cells using high resolution flow cytometry and proteomic and phospho-proteomic studies. Our preliminary results describe a reduced number of molecules that are activated in response to IL-6 in T cells, that exquisitely inter-relate to produce the plethora of activities exhibited by this cytokine.
For objective two, we have successfully displayed IL-6 in our protein engineering platform and show that it can bind its cognate receptors. Additionally, we have generated a library of IL-6 variants and select it against its surface receptor to isolate IL-6 variants binding with a range of affinities to their receptor. We are currently characterizing the properties of these ligands in adequate model systems. Preliminary results, suggest that the half-life of the cytokine-cytokine receptor complex play a critical contribution in determining the nature and extent of the signaling signature induced by cytokines, which in turn result in a more defined set of biological responses induced by these new engineered ligands.
Final results
To date we lack a clear understanding on how cytokines trigger unique signaling signatures and biological responses. This has hindered our ability to translate this important family of ligands to the clinic. The outcome of this program will move significantly forward our understanding of cytokine biology and provide us with a set of biophysical and structural boundaries determining signal activation potency and nature by cytokines. In principle, this could be exploited to engineer synthetic agonists with tailored functional properties to interrogate and manipulate cellular responses promoted by cytokines for potential pharmaceutical applications.