Functional proteomics to explore how endocytic recycling of receptor tyrosine kinases specifies cellular responses
Endocytic trafficking of receptor tyrosine kinases (RTKs) from and to the plasma membrane elicit specific and dynamic intracellular signalling cascades and ultimately affect cellular responses (i.e. cell proliferation and migration) (Sigismund et al., 2012). Despite the importance of endocytosis during development and in physio-pathological processes, mechanisms underlying the recycling of RTKs to the plasma membrane after internalization are still poorly understood. High-resolution examination of key regulators of receptor recycling-mediated cellular outputs is crucial for identifying novel signaling nodes amenable to therapeutic intervention in those human diseases, including cancer, characterized by aberrant RTK trafficking.
Omics methodologies are transforming modern biology. In particular, functional proteomics integrates the wide-ranging identification and quantification of signaling events by Mass Spectrometry (MS)-based proteomics with bioinformatics and functional assays in cell culture and/or tissues (Francavilla et al., 2013). Such a comprehensive approach which enables the characterization of thousands of proteins, their post-translational modifications, such as phosphorylation and ubiquitylation, and interaction partners, has been successfully used for studying, among others, Fibroblast Growth Factor Receptor (FGFR) or Nerve Growth Factor (NGF) signaling at an unprecedented level of depth (Emdal et al., 2015; Francavilla et al., 2013). Moreover, cell signaling dynamics can be analyzed at multiple levels over different time scales by temporal proteomics (Francavilla et al., 2014).
The group focuses on the FGFR family composed of seven receptors and eighteen secreted ligands because this family of RTKs have major roles during development (Dorey and Amaya, 2012), is deregulated in several genetic diseases and in cancer (Fearon et al., 2013; Katoh, 2008), and represent a relevant system to study how different ligand-receptor pairs and their trafficking routes dynamically regulate a great variety of cellular outputs.
By combining functional proteomics with in vivo studies, our research aims at understanding:
1. why different ligands of a receptor either promote receptor degradation or recycling;
2. which are the underlying molecular mechanisms and key regulators;
3. what are the differences between receptor signal from different sub-cellular compartments;
4. whether signals controlling long-term responses can be encoded by the trafficking of receptors;
5. how these signals can be manipulated in vivo.