Phosphorylation and lipid raft association of fibroblast growth factor receptor-2 in oligodendrocytes
| Autor: | Cecilia B. Marta, Melissa Bryant, F. S. Kim, Rashmi Bansal |
|---|---|
| Rok vydání: | 2009 |
| Předmět: |
Telencephalon
MAPK/ERK pathway Biology Article Mice Cellular and Molecular Neuroscience Membrane Microdomains medicine Animals Protein Isoforms Receptor Fibroblast Growth Factor Type 1 Phosphorylation Receptor Fibroblast Growth Factor Type 2 Extracellular Signal-Regulated MAP Kinases Protein kinase B Lipid raft Cells Cultured Myelin Sheath PI3K/AKT/mTOR pathway Mice Knockout MAP Kinase Kinase Kinases Oligodendrocyte Rats Cell biology Oligodendroglia medicine.anatomical_structure Neurology Fibroblast growth factor receptor Astrocytes Tyrosine lipids (amino acids peptides and proteins) Signal transduction Proto-Oncogene Proteins c-akt Signal Transduction |
| Zdroj: | Glia. 57:935-946 |
| ISSN: | 1098-1136 0894-1491 |
| DOI: | 10.1002/glia.20818 |
| Popis: | Fibroblast growth factors (FGFs) and their receptors (FGFRs) initiate diverse cellular responses that contribute to the regulation of oligodendrocyte (OL) function. In order to understand the mechanisms by which FGFRs elicit these cellular responses, we investigated the phosphorylation of signal transduction proteins and the role of cholesterol-glycosphingolipid-enriched “lipid raft” microdomains in differentiated OLs. Surprisingly, we found that the most abundant tyrosine-phosphorylated protein in OLs was the 120-kd isoform of FGFR2 and that it was phosphorylated even in the absence of FGF2, suggesting a potential ligand-independent function for this receptor. Furthermore, FGFR2, but not FGFR1, was associated with lipid raft microdomains in OLs and myelin (but not in astrocytes). This provides the first evidence for the association of FGFR with TX-100-insoluble lipid raft fractions. FGFR2 phosphorylated the key downstream target, FRS2 in OLs. Raft disruption resulted in loss of phosphorylated FRS2 from lipid rafts, coupled with the loss of Akt but not of Mek or Erk phosphorylation. This suggests that FGFR2-FRS2 signaling in lipid rafts operates via the PI3-Kinase/Akt pathway rather than the Ras/Mek/Erk pathway, emphasizing the importance of microenvironments within the cell membrane. Also present in lipid rafts in OLs and myelin, but not in astrocytes, was a novel 52-kd isoform of FGFR2 that lacked the extracellular ligand-binding region. These results demonstrate that FGFR2 in OLs and myelin possess unique characteristics that are specific both to receptor type and to OLs and provide a novel mechanism to elicit distinct cellular responses that mediate both FGF-dependent and -independent functions. |
| Databáze: | OpenAIRE |
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