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Kinase inhibitors abrogate IFN-gamma-induced class II transactivator and class II MHC gene expression in astroglioma
N J Van Wagoner1, G M O'Keefe, E N Benveniste
1Department of Cell Biology, University of Alabama at Birmingham, 35294-0005, USA.
Abstract:
Multiple kinase events, involving both tyrosine (tyr) kinase and serine/threonine (ser/thr) kinase activity, are required for IFN-gamma-induced class II MHC mRNA and protein expression in primary rat astrocytes. In this study, we examined the necessity of ser/thr and tyr kinase activity for IFN-gamma-induced stimulation of class II MHC gene expression in the human astroglioma cell lines CRT and CH235, as well as the involvement of these kinases in IFN-gamma-induced expression of the class II transactivator (CIITA), a protein critical for IFN-gamma-induced transcription of class II MHC genes. We show that general ser/thr kinase inhibitors, inhibitors of the ser/thr kinase mitogen-activated protein kinase (MAPK), and tyr kinase inhibitors reduce IFN-gamma-induced class II MHC mRNA and protein expression in a dose-dependent manner. As well, these inhibitors abrogate IFN-gamma-induced CIITA mRNA expression in the astroglioma cell lines. We have further demonstrated that cells constitutively expressing the CIITA protein (2fTGH.CIITA) show no decrease in CIITA or class II MHC mRNA expression in the presence of ser/thr and tyr kinase inhibitors. Collectively, these data indicate that ser/thr kinase activity, possibly MAPK, and tyr kinase activity are required for IFN-gamma-induced expression of CIITA mRNA, and the subsequent expression of class II MHC genes.
Insights
Interferon-gamma (IFN-γ) requires both serine/threonine and tyrosine kinase activity for class II MHC gene expression. These kinases are essential for inducing CIITA mRNA, which drives class II MHC expression in astroglioma cells.
Area of Science:
- Immunology
- Molecular Biology
- Neuroscience
Background:
- Interferon-gamma (IFN-γ) induces class II Major Histocompatibility Complex (MHC) expression.
- Class II MHC expression is critical for antigen presentation.
- The class II transactivator (CIITA) is essential for IFN-γ-induced class II MHC gene transcription.
Purpose of the Study:
- To investigate the role of serine/threonine (ser/thr) and tyrosine (tyr) kinase activity in IFN-γ-induced class II MHC expression.
- To determine if these kinase activities are necessary for IFN-γ-induced CIITA expression in human astroglioma cell lines.
Main Methods:
- Utilized human astroglioma cell lines (CRT and CH235).
- Administered ser/thr kinase inhibitors, mitogen-activated protein kinase (MAPK) inhibitors, and tyr kinase inhibitors.
- Assessed class II MHC mRNA and protein expression.
- Evaluated CIITA mRNA expression.
- Used cells constitutively expressing CIITA (2fTGH.CIITA) as a control.
Main Results:
- General ser/thr kinase inhibitors, MAPK inhibitors, and tyr kinase inhibitors dose-dependently reduced IFN-γ-induced class II MHC mRNA and protein expression.
- These inhibitors abrogated IFN-γ-induced CIITA mRNA expression in astroglioma cells.
- Cells with constitutive CIITA expression showed no reduction in CIITA or class II MHC mRNA with kinase inhibitors.
Conclusions:
- Ser/thr kinase activity, potentially involving MAPK, and tyr kinase activity are required for IFN-γ-induced CIITA mRNA expression.
- CIITA induction by IFN-γ necessitates both ser/thr and tyr kinase signaling pathways.
- These kinase activities are upstream of CIITA and essential for subsequent class II MHC gene expression.