title: Insulin growth factor signaling mediates neuron-like differentiation of adipose-tissue-derived stem cells.
abstract: Our previous study showed that adipose tissue-derived stem cells (ADSC) could be induced by isobutylmethylxanthine (IBMX) to differentiate into neuron-like cells. In the present study, ADSC were treated with IBMX in the presence or in the absence of each of eight specific inhibitors of different signaling pathways (JAK/STAT, PKA, PI3K, MEK, Wnt/Frizzled, ERK/MAPK, TGF-beta, and insulin growth factor [IGF]-I). PPP, a specific inhibitor of IGF-I signaling, was the only inhibitor that showed significant inhibition of IBMX-induced ADSC neuronal differentiation, as determined by changes in cell morphology in the initial screening. Further examination by immunofluorescence staining showed that the neuronal marker, beta-III-tubulin, was highly induced in IBMX-treated ADSC, and the induction was significantly suppressed by PPP. Western blotting, followed by densitometry showed that PPP suppressed IBMX-induced beta-III-tubulin expression by 43%, 88%, and 84% when used to treat the cells for 1, 3, and 24 hr, respectively. Treatment of ADSC with IBMX also led to the phosphorylation of IGF-I receptor at tyrosine 1136 (Y1136), as determined by immunofluorescence staining with an antibody that reacts specifically with Y1136. This effect was also abrogated by PPP. Thus, the IBMX-induced neuron-like differentiation of ADSC is mediated by IGF signaling through the phosphorylation of IGF-IR at Y1136.
authors.affiliation: Knuppe Molecular Urology Laboratory Department of Urology, School of Medicine, University of California San Francisco, CA 94143-0738, USA.
authors.forename: Hongxiu
authors.initials: H
authors.lastname: Ning
authors.forename: Guiting
authors.initials: G
authors.lastname: Lin
authors.forename: Thomas
authors.initials: T
authors.lastname: Fandel
authors.forename: Lia
authors.initials: L
authors.lastname: Banie
authors.forename: Tom F
authors.initials: TF
authors.lastname: Lue
authors.forename: Ching-Shwun
authors.initials: CS
authors.lastname: Lin
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000273:Adipose Tissue / Q000166:cytology*; D053687:Adult Stem Cells / Q000166:cytology / Q000187:drug effects*; D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D003470:Culture Media / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000166:cytology*; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000737:chemistry; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011499:Protein Processing, Post-Translational; D051381:Rats; D017526:Receptor, IGF Type 1 / Q000187:drug effects / Q000502:physiology*; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D003470:Culture Media; D047428:Protein Kinase Inhibitors; C415032:picropodophyllin; D019000:Phosphotyrosine; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1; D011034:Podophyllotoxin; D015056:1-Methyl-3-isobutylxanthine