Brain-derived neurotrophic factor induces phosphorylation of fibroblast growth factor receptor substrate 2.
Brain-derived neurotrophic factor (BDNF) promotes neuronal survival. Gaining an understanding of how BDNF, via the tropomyosin-related kinase B (TRKB) receptor, elicits specific cellular responses is of contemporary interest. Expression of mutant TrkB in fibroblasts, where tyrosine 484 was changed to phenylalanine, abrogated Shc association with TrkB, but only attenuated and did not block BDNF-induced phosphorylation of mitogen-activated protein kinase (MAPK). This suggests there is another BDNF-induced signaling mechanism for activating MAPK, which compelled a search for other TrkB substrates. BDNF induces phosphorylation of fibroblast growth factor receptor substrate 2 (FRS2) in both fibroblasts engineered to express TrkB and human neuroblastoma (NB) cells that naturally express TrkB. Additionally, BDNF induces phosphorylation of FRS2 in primary cultures of cortical neurons, thus showing that FRS2 is a physiologically relevant substrate of TrkB. Data are presented demonstrating that BDNF induces association of FRS2 with growth factor receptor-binding protein 2 (GRB2) in cortical neurons, fibroblasts, and NB cells, which in turn could activate the RAS/MAPK pathway. This is not dependent on Shc, since BDNF does not induce association of Shc and FRS2. Finally, the experiments suggest that FRS2 and suc-associated neurotrophic factor-induced tyrosine-phosphorylated target are the same protein.
Easton
J B
JB
Department of Molecular Pharmacology, St. Jude Children's Research Hospital, Memphis, Tennessee 38105-2794, USA.
Moody
N M
NM
Zhu
X
X
Middlemas
D S
DS
D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002460:Cell Line; D051380:GRB2 Adaptor Protein; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D010649:Phenylalanine / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism; D051381:Rats; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics; D020801:Receptor, Ciliary Neurotrophic Factor; D017475:Receptors, Nerve Growth Factor / Q000235:genetics; D014443:Tyrosine / Q000235:genetics / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; D019208:Brain-Derived Neurotrophic Factor; C106534:FRS2 protein, human; D051380:GRB2 Adaptor Protein; C495948:GRB2 protein, human; C495950:Grb2 protein, rat; D008565:Membrane Proteins; D010750:Phosphoproteins; D011506:Proteins; D020801:Receptor, Ciliary Neurotrophic Factor; D017475:Receptors, Nerve Growth Factor; D014443:Tyrosine; D010649:Phenylalanine; D020794:Receptor Protein-Tyrosine Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases