Interferon-triggered transcriptional cascades in the oligodendroglial lineage: A comparison of induction of MHC class II antigen between oligodendroglial progenitor cells and mature oligodendrocytes

Interferon-γ induces major histocompatibility complex class II (MHC-II) in proliferating oligodendroglial progenitor cells (OPC), but to a much lesser extent in mature oligodendrocytes. Interferon-β has virtually no effects on MHC-II induction even in OPC. Interferon-γ-mediated transcriptional induction of CIITA, a critical regulator of MHC-II induction, was 6-fold lower in mature oligodendrocytes than in OPC, and entirely dependent on promoter IV, suggesting that the transcriptional activity of promoter IV is down-regulated after differentiation. The distinct difference in MHC-II induction between interferon-γ and interferon-β is attributed to transient interferon-β-mediated activation of STAT1-IRF1 signaling compared to the sustained interferon-γ-mediated activation.