title: Constitutively activated FGFR3 mutants signal through PLCgamma-dependent and -independent pathways for hematopoietic transformation.
abstract: Ectopic expression of fibroblast growth factor receptor 3 (FGFR3) associated with t(4;14) has been implicated in the pathogenesis of human multiple myeloma. Some t(4;14) patients have activating mutations of FGFR3, of which a minority are K650E (thanatophoric dysplasia type II [TDII]). To investigate the role of autophosphorylated tyrosine residues in FGFR3 signal transduction and transformation, we characterized a series of FGFR3 TDII mutants with single or multiple Y-->F substitutions. Phenylalanine substitution of Y760, essential for phospholipase Cgamma (PLCgamma) binding and activation, significantly attenuated FGFR3 TDII-mediated PLCgamma activation, as well as transformation in Ba/F3 cells and a murine bone marrow transplant leukemia model. In contrast, single substitution of Y577, Y724, or Y770 had minimal to moderate effects on TDII-dependent transformation. Substitution of all 4 non-activation loop tyrosine residues significantly attenuated, but did not abolish, TDII transforming activity. Similar observations were obtained in the context of a constitutively activated fusion TEL-FGFR3 associated with t(4;12)(p16;p13) peripheral T-cell lymphomas. Moreover, 2 independent EmuSR-FGFR3 TDII transgenic mouse lines developed a pro-B-cell lymphoma, and PLCgamma was highly activated in primary lymphoma cells as assessed by tyrosine phosphorylation. These data indicate that engagement of multiple signaling pathways, including PLCgamma-dependent and PLCgamma-independent pathways, is required for full hematopoietic transformation by constitutively activated FGFR3 mutants.
authors.affiliation: Howard Hughes Medical Institute, Harvard Medical Scgool, Boston, MA, USA. jchen@emory.edu
authors.forename: Jing
authors.initials: J
authors.lastname: Chen
authors.forename: Ifor R
authors.initials: IR
authors.lastname: Williams
authors.forename: Benjamin H
authors.initials: BH
authors.lastname: Lee
authors.forename: Nicole
authors.initials: N
authors.lastname: Duclos
authors.forename: Brian J P
authors.initials: BJ
authors.lastname: Huntly
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Donoghue
authors.forename: D Gary
authors.initials: DG
authors.lastname: Gilliland
mesh_terms: D019943:Amino Acid Substitution; D000818:Animals; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D015972:Gene Expression Regulation, Neoplastic; D051379:Mice; D008822:Mice, Transgenic; D009101:Multiple Myeloma / Q000473:pathology / Q000503:physiopathology*; D016297:Mutagenesis, Site-Directed; D015514:Oncogene Proteins, Fusion / Q000235:genetics; D051966:Phospholipase C gamma; D011505:Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism*; D051498:Receptor, Fibroblast Growth Factor, Type 3; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D010738:Type C Phospholipases / Q000378:metabolism*; D014443:Tyrosine / Q000235:genetics
chemical_list: D015514:Oncogene Proteins, Fusion; D017468:Receptors, Fibroblast Growth Factor; D014443:Tyrosine; C496366:Fgfr3 protein, mouse; D011505:Protein-Tyrosine Kinases; D051498:Receptor, Fibroblast Growth Factor, Type 3; D010738:Type C Phospholipases; D051966:Phospholipase C gamma