Growth factors signaling through the cell-surface receptor tyrosine kinases (RTKs) represent one of the most critical pathways in the cellular and inter-cellular regulation of vertebrate biological systems. Defects/malfunctions of the class III RTKs, such as the Stem Cell Factor (SCF) receptor KIT, the Macrophage Colony Stimulating Factor (MCSF) receptor FMS, and the FLT3 Ligand (FLT3L) receptor FLT3, contribute to the genesis and development of many types of cancers such as leukemia, gastrointestinal stromal tumor (GIST), and others. These receptors are ideal targets for cancer therapies, but the mechanistic basis underlying their ligand recognition and activation is incompletely understood. Our long-term goal is to elucidate the structural mechanisms used by these receptors in cellular regulation and malignancies. The project will perform a thorough analysis of the whole activation process of class III RTKs: how these receptors maintain static states when the ligands are not present, how their extra cellular domains recognize ligands, and what are the conformational changes required for receptor activation.
The specific aims are: (1) Biochemical reconstitution and structural analysis of the complex between KIT and its ligand SCF. Crystals of the SCF/KIT complex that diffract X-rays to 3.2 Angstroms resolution have been obtained. The structure will be solved by multi-wavelength anomalous diffraction (MAD). (2) Biochemical reconstitution and structural analysis of the complex between FMS and its ligand MCSF. Crystals of the MCSF/FMS complex that diffract to 2.4 Angstroms resolution have been obtained. The structure was determined by a combination of partial molecular replacement and single isomorphous replacement with anomalous scattering (SIRAS);refinement is in progress. (3) Biochemical characterization and structural analysis of the complex between FLT3 and its ligand FLT3L. Small crystals of the FLT3L/FLT3 complex have been obtained recently. (4) Investigation of the binding specificity and energetics of the receptor/ligand interactions through protein engineering of the receptor/ligand interfaces. These studies will elucidate novel structural mechanisms that will lay the groundwork for therapeutic development to treat class III-RTK-related cancers.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM078055-05
Application #
7894556
Study Section
Macromolecular Structure and Function C Study Section (MSFC)
Program Officer
Maas, Stefan
Project Start
2006-08-01
Project End
2012-01-31
Budget Start
2010-08-01
Budget End
2012-01-31
Support Year
5
Fiscal Year
2010
Total Cost
$259,618
Indirect Cost
Name
Northwestern University at Chicago
Department
Pharmacology
Type
Schools of Medicine
DUNS #
005436803
City
Chicago
State
IL
Country
United States
Zip Code
60611
Chen, Po-Han; Chen, Xiaoyan; He, Xiaolin (2013) Platelet-derived growth factors and their receptors: structural and functional perspectives. Biochim Biophys Acta 1834:2176-86
Liu, Heli; Leo, Cindy; Chen, Xiaoyan et al. (2012) The mechanism of shared but distinct CSF-1R signaling by the non-homologous cytokines IL-34 and CSF-1. Biochim Biophys Acta 1824:938-45
Shim, Ann Hye-Ryong; Chang, Rhoda Ahn; Chen, Xiaoyan et al. (2012) Multipronged attenuation of macrophage-colony stimulating factor signaling by Epstein-Barr virus BARF1. Proc Natl Acad Sci U S A 109:12962-7
Liu, Heli; Juo, Z Sean; Shim, Ann Hye-Ryong et al. (2010) Structural basis of semaphorin-plexin recognition and viral mimicry from Sema7A and A39R complexes with PlexinC1. Cell 142:749-61
Chen, Xiaoyan; Liu, Heli; Shim, Ann H R et al. (2008) Structural basis for synaptic adhesion mediated by neuroligin-neurexin interactions. Nat Struct Mol Biol 15:50-6
Chen, Xiaoyan; Liu, Heli; Focia, Pamela J et al. (2008) Structure of macrophage colony stimulating factor bound to FMS: diverse signaling assemblies of class III receptor tyrosine kinases. Proc Natl Acad Sci U S A 105:18267-72