Epidermal Growth Factor Modulation of MO3.13 Cells and Effects on Insulin/IGF and Notch Networks

Background/Objectives: Oligodendrocyte maturation and function are stimulated by insulin and insulin-like growth factor (IGF) signaling through Akt-mTOR and Notch. Dysregulation of these pathways is associated with impaired white matter development; yet, treatment with insulin-sensitizing agents failed to restore oligodendrocyte function, leading to the hypothesis that additional signaling pathways are needed for oligodendrocyte function. Methods: Experiments were conducted using human MO3.13 cells to investigate the role of epidermal growth factor receptor (EGFR) expression and signaling as potential mediators of immature oligodendroglia function and mechanistic interactions with insulin/IGF and Notch pathways. Methodologies included cell function, cytomorphology, immunoassays, and RNA hybridization assays. Results: Although EGF, TGF-α, and TGF-β increased the relative levels of EGFR tyrosine phosphorylation (pY-EGFR), MTT activity, and proliferating cell nuclear antigen, EGF and TGF-β increased pY-Erk MAPK and GALC expression and reduced activated Caspase 3, while EGF selectively increased CNPase, MAG, MOG, and MBP. EGF and TGF-α stimulated IGF2, INSULINR, IGF1R, IGF2R, IRS1, and IRS2 mRNA transcripts, while TGF-α and TGF-β increased expression of NOTCH1, JAGGED1, HES1, HEY1, and HIF1A Notch network genes. Conclusions: EGF, TGF-α, and TGF-β differentially modulated the effects of EGFR stimulation on oligodendroglia-related functions, including protein expression. The findings highlight the potential importance of EGFR pathway signaling and its interactions with insulin/IGF and Notch pathways for regulating oligodendrocyte functions during development.