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. Author manuscript; available in PMC: 2008 Jun 21.
Published in final edited form as: Neurosci Lett. 2007 May 16;421(1):27–32. doi: 10.1016/j.neulet.2007.05.020

Figure 1. OP differentiation into oligodendrocytes.

Figure 1

OP cells were infected with retroviral constructs to modulate receptor and ligand elements of the FGF2 and notch signaling pathways. OP differentiation into oligodendrocytes was monitored by O1 immunostaining. A: OP cells infected with retrovirus expressing a dominant negative form of fibroblast growth factor receptor (FGFRdn) and green fluorescent protein reporter (GFP; green). After 3 days of co-culture with Jagged 1 expressing fibroblast cells (not fluorescently labeled) many of the retrovirally labeled cells have immature characteristics (green; asterisks) in contrast to the differentiated oligodendrocyte (arrowhead) with highly branched processes and immunolabeling for O1 (red). Scale bar = 50 μm. B: OP cell infected with retrovirus expressing the intracellular domain of Notch 1 (Notch1IC), a constitutively active form, and GFP (B, green) has an immature morphology and lacks O1 immunoreactivity (red absent). Scale bar = 15 μm. C: OP cells infected with a retrovirus expressing a dominant negative form of mastermind-like1 (Maml1dn), a co-activator of notch target genes, and GFP (green) exhibit elaborate processes and O1 immunoreactivity (red), indicative of differentiation into mature oligodendrocytes. Scale bar = 50 μm. D, E, F: Quantitation of the proportion of O1 immunolabeled cells among retrovirally infected cells identified by expression of the GFP reporter. D: OP cells infected with retrovirus and then co-cultured with a fibroblast line expressing Jagged1 (+) or the parental L cell line (−). Cells were grown in defined medium with (+) or without (−) FGF2. Co-culture of OP cells with fibroblasts expressing Jagged1 decreased the proportion of OP cells that developed O1 immunoreactivity (a; p < 0.01). FGF2 severely reduced O1 acquisition (b; p < 0.001), which was abrogated by FGFRdn transduction. FGF2 further decreased O1 acquisition as compared to co-culture with Jagged1 expressing cells (c; p < 0.001). E: Notch1IC transduction strongly inhibited OP differentiation (p<0.001), compared with control retrovirus, and was not further reduced with FGF2 treatment. F: Upper panel shows immunostaining for endogenous Maml1 expression in OP cells. Scale bar = 50 μm. Lower panel shows that FGF2 inhibition of OP differentiation was significantly perturbed by Maml1dn transduction (p < 0.05 vs control virus). Values (mean ± standard error of the proportion) are from three independent experiments with at least 300 GFP+ cells counted for each condition.