Activation and Signaling Mechanism of the RET Tyrosine Kinase Receptor

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DESCRIPTION (provided by applicant): This fellowship will support the research aims and training of a graduate student in the laboratory of Professor Adrian Whitty at Boston University. Many forms of cancer are caused by aberrant signaling of growth factor (GF) receptors. Consequently, achieving an improved understanding of GF receptor activation and function continues to give rise to improved approaches to cancer treatment. However, many basic questions about the molecular mechanisms of GF receptor activation and signaling remain unanswered. We propose to develop new methods for the quantitative mechanistic study of GF receptor signaling, using the multicomponent RE-arranged during Transfection (RET) receptor as a test case. RET is a receptor tyrosine kinase that is the receptor for the glial cell-line deried neurotrophic factor (GDNF) family of neurotrophins. Deregulation of RET signaling is causally involved in several types of cancer, including multiple endocrine neoplasias (MEN) 2A and -2B, medullary thyroid carcinoma, parathyroid hyperplasia, and phaeochromocytoma. We propose to characterize the molecular mechanisms of RET activation and signaling by pursuing following three aims: 1) genetically encoded fluorescence resonance energy transfer (FRET) constructs will be used to develop a reporter system for monitoring RET association events on the surface of live cells using flow cytometry. 2) The FRET reporter constructs developed in Aim 1, will be used to address key questions concerning the mechanism of RET activation on live cells. These questions include addressing the difficult and longstanding uncertainty concerning whether GF receptors function by ligand-induced receptor dimerization, or alternatively by causing a structural rearrangement within pre-associated receptor dimers or oligomers. 3) The mechanisms and impact of crosstalk between RET and vascular endothelial growth factor receptor 2 (VEGFR2) will be explored, to establish at what levels in RET signaling crosstalk occurs and how the effects on RET function depend on the level of VEGFR2 stimulation. Collectively, these three aims will establish new methods to elucidate mechanisms of GF receptor activation, and will establish the mechanisms and impact of crosstalk between two different families of GF receptors. This research will help the fellow achieve her career goal, which is to lead an academic research group that addresses important biological problems relating to human health. She plans to address these problems by working at the molecular, cellular and in vivo levels of systems complexity, employing primarily a hypothesis-driven and (where appropriate) a quantitative perspective. The training plan in her graduate work will enable her to focus on developing her knowledge and capabilities of molecular and cellular approaches, with the idea that she will go on to encompass in vivo techniques and perspectives through post doctoral study in a suitable laboratory. Working together, the candidate and her sponsor have developed a highly effective plan for how to achieve the training she will need to meet her long-term career objectives.