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Crystal structure of the Sema-PSI extracellular domains of human RON receptor tyrosine kinase
Structural highlights
FunctionRON_HUMAN Receptor tyrosine kinase that transduces signals from the extracellular matrix into the cytoplasm by binding to MST1 ligand. Regulates many physiological processes including cell survival, migration and differentiation. Ligand binding at the cell surface induces autophosphorylation of RON on its intracellular domain that provides docking sites for downstream signaling molecules. Following activation by ligand, interacts with the PI3-kinase subunit PIK3R1, PLCG1 or the adapter GAB1. Recruitment of these downstream effectors by RON leads to the activation of several signaling cascades including the RAS-ERK, PI3 kinase-AKT, or PLCgamma-PKC. RON signaling activates the wound healing response by promoting epithelial cell migration, proliferation as well as survival at the wound site. Plays also a role in the innate immune response by regulating the migration and phagocytic activity of macrophages. Alternatively, RON can also promote signals such as cell migration and proliferation in response to growth factors other than MST1 ligand.[1] [2] [3] Publication Abstract from PubMedHuman RON (Recepteur d'Origine Nantais) receptor tyrosine kinase is a cell surface receptor for Macrophage Stimulating Protein (MSP). RON mediates signal transduction pathways that regulate cell adhesion, invasion, motility and apoptosis processes. Elevated levels of RON and its alternatively spliced variants are implicated in the progression and metastasis of tumor cells. The binding of MSP alpha/beta heterodimer to the extracellular region of RON receptor induces receptor dimerization and activation by autophosphorylation of the intracellular kinase domains. The ectodomain of RON, containing the ligand recognition and dimerization domains, is composed of a semaphorin (Sema), Plexins-Semaphorins-Integrins domain (PSI), and four Immunoglobulins-Plexins-Transcription factor (IPT) domains. High affinity association between MSP and RON is mediated by the interaction between MSP beta-chain and RON Sema, although RON activation requires intact RON and MSP proteins. Here, we report the structure of RON Sema-PSI domains at 1.85 A resolution. RON Sema domain adopts a seven-bladed beta-propeller fold, followed by disulfide bond rich, cysteine-knot PSI motif. Comparison with the homologous Met receptor tyrosine kinase reveals that RON Sema-PSI contains distinguishing secondary structural features. These define the receptors' exclusive selectivity towards their respective ligands, RON for MSP and Met for HGF. The RON Sema-PSI crystal packing generates a homodimer with interface formed by the Sema domain. Mapping of the dimer interface using the RON homology to Met, MSP homology to Hepatocyte Growth Factor (HGF), and the structure of the Met/HGF complex shows the dimer interface overlapping with the putative MSPbeta binding site. The crystallographically determined RON Sema-PSI homodimer may represent the dimer assembly that occurs during ligand-independent receptor activation and/or the inhibition of the constitutive activity of RONDelta160 splice variant by the soluble RON splice variant, RONDelta85. Crystal Structure of the Sema-PSI Extracellular Domain of Human RON Receptor Tyrosine Kinase.,Chao KL, Tsai IW, Chen C, Herzberg O PLoS One. 2012;7(7):e41912. Epub 2012 Jul 25. PMID:22848655[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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