The fibroblast growth factor receptor substrate 3 adapter is a developmentally regulated microtubule-associated protein expressed in migrating and differentiated neurons.
Fibroblast growth factor (FGF) mediated signaling is essential to many aspects of neural development. Activated FGF receptors signal primarily through the FGF receptor substrate (Frs) adapters, which include Frs2/Frs2alpha and Frs3/Frs2beta. While some studies suggest that Frs3 can compensate for the loss of Frs2 in transfected cells, the lack of an effective Frs3 specific antibody has prevented efforts to determine the role(s) of the endogenous protein. To this end, we have generated a Frs3 specific antibody and have characterized the pattern of Frs3 expression in the developing nervous system, its subcellular localization as well as its biochemical properties. We demonstrate that Frs3 is expressed at low levels in the ventricular zone of developing cortex, between E12 and E15, and it co-localizes with nestin and acetylated alpha-tubulin in radial processes in the ventricular/subventricular zones as well as with betaIII tubulin in differentiated cortical neurons. Subcellular fractionation studies demonstrate that endogenous Frs3 is both soluble and plasma membrane associated while Frs3 expressed in 293T cells associates exclusively with lipid rafts. Lastly, we demonstrate that neuronal Frs3 binds microtubules comparable to the microtubule-associated protein, MAP2, while Frs2 does not. Collectively, these data suggest that neuronal Frs3 functions as a novel microtubule binding protein and they provide the first biochemical evidence that neuronal Frs3 is functionally distinct from Frs2/Frs2alpha.
Hryciw
Todd
T
Molecular Brain Research Group, Robarts Research Institute, London, Ontario, Canada.
MacDonald
James I S
JI
Phillips
Renée
R
Seah
Claudia
C
Pasternak
Stephen
S
Meakin
Susan O
SO
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000502:physiology; D002454:Cell Differentiation / Q000187:drug effects / Q000502:physiology*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development; D000242:Cyclic AMP / Q000494:pharmacology; D004622:Embryo, Mammalian; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects / Q000502:physiology*; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D006624:Hippocampus; D006801:Humans; D066298:In Vitro Techniques; D019394:Ki-67 Antigen / Q000378:metabolism; D052118:Lysosomal-Associated Membrane Protein 1 / Q000378:metabolism; D021962:Membrane Microdomains / Q000378:metabolism; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D011485:Protein Binding; D020825:T-Box Domain Proteins / Q000378:metabolism; D014404:Tubulin / Q000378:metabolism
D048868:Adaptor Proteins, Signal Transducing; C491198:Eomes protein, mouse; C113566:FRS3 protein, human; D005904:Glial Fibrillary Acidic Protein; D019394:Ki-67 Antigen; D052118:Lysosomal-Associated Membrane Protein 1; D008869:Microtubule-Associated Proteins; D020825:T-Box Domain Proteins; D014404:Tubulin; C462941:beta3 tubulin, mouse; D000242:Cyclic AMP