title: NT3 inhibits FGF2-induced neural progenitor cell proliferation via the PI3K/GSK3 pathway.
abstract: Neurotrophin 3 (NT3), a member of the neurotrophin family, antagonizes the proliferative effect of fibroblast growth factor 2 (FGF2) on cortical precursors. However, the mechanism by which NT3 inhibits FGF2-induced neural progenitor (NP) cell proliferation is unclear. Here, using an FGF2-dependent rat neurosphere culture system, we found that NT3 inhibits both FGF2-induced neurosphere growth and bromodeoxyuridine (BrdU) incorporation in a dose-dependent manner. U0126, a mitogen-activated protein kinase kinase 1/2 (MEK1/2) inhibitor, and LY294002, a phosphatidylinositol 3-kinase (PI3K) inhibitor, both inhibited FGF2-induced BrdU incorporation, suggesting that the extracellular signal-regulated kinase1/2 (ERK1/2) and PI3K pathways are required for FGF2-induced NP cell proliferation. NT3 significantly inhibited FGF2-induced phosphorylation of Akt and glycogen synthase kinase 3beta (GSK3beta), a downstream kinase of Akt, whereas phosphorylation of ERK1/2 was unaffected. The inhibitory effect of NT3 on FGF2-induced NP cell proliferation was abolished by LY294002, and treatment with SB216763, a specific GSK3 inhibitor, antagonized the NT3 effect, rescuing both neurosphere growth and BrdU incorporation. Moreover, experiments with anti-NT3 antibody revealed that endogenous NT3 also plays a role in inhibiting FGF2-induced NP cell proliferation, and that anti-NT3 antibody enhanced phospho-Akt and phospho-GSK3beta levels in the presence of FGF2. These findings indicate that FGF2-induced NP cell proliferation is inhibited by NT3 via the PI3K/GSK3 pathway.
authors.affiliation: Institute of Neuroscience, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Graduate School of Chinese Academy of Sciences, Shonghai, China.
authors.forename: Lu
authors.initials: L
authors.lastname: Jin
authors.forename: Xinhua
authors.initials: X
authors.lastname: Hu
authors.forename: Linyin
authors.initials: L
authors.lastname: Feng
mesh_terms: D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D049109:Cell Proliferation / Q000187:drug effects; D002867:Chromones / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology; D009025:Morpholines / Q000494:pharmacology; D009474:Neurons / Q000166:cytology*; D020933:Neurotrophin 3 / Q000276:immunology / Q000494:pharmacology*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D017207:Rats, Sprague-Dawley; D018874:Spheroids, Cellular; D013234:Stem Cells / Q000166:cytology*
chemical_list: D000906:Antibodies; D002867:Chromones; D004791:Enzyme Inhibitors; D016222:Fibroblast Growth Factor 2; D038362:Glycogen Synthase Kinase 3; D009025:Morpholines; D020933:Neurotrophin 3; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D051057:Proto-Oncogene Proteins c-akt; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C494920:Akt1 protein, rat