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Published on: April 11, 2014
Ascorbic Acid Promotes KIR Demethylation during Early NK Cell Differentiation.
Cheng-Ying Wu1, Bin Zhang1, Hansol Kim1
1Department of Medicine, University of Minnesota, Minneapolis, MN 55455; and.
Variegated killer Ig-like receptor (KIR) expression in NK cells is regulated by DNA demethylation. Ascorbic acid treatment in vitro induces KIR promoter demethylation and expression in immature NK cells.
Area of Science:
- Immunology
- Epigenetics
- Cell Biology
Background:
- Killer Ig-like receptors (KIR) exhibit variegated expression in mature human NK cells and CD8+ T cells.
- Allele-specific KIR expression is epigenetically regulated by DNA methylation in proximal promoter regions.
- The developmental stage and mechanism of KIR promoter demethylation during NK cell maturation remain unknown.
Purpose of the Study:
- To investigate the mechanism of KIR promoter demethylation during human NK cell development.
- To explore the role of ten-eleven translocation (TET) enzymes and ascorbic acid in regulating KIR expression.
Main Methods:
- Analysis of KIR promoter methylation in distinct human NK cell subsets (CD56bright and CD56dim).
- Ex vivo culture of CD56bright NK cells with ascorbic acid and assessment of KIR expression and promoter demethylation.
- Investigation of TET enzymes, Runx3, and ascorbic acid's effects on KIR expression via overexpression studies.
Main Results:
- KIR proximal promoters are methylated in CD56bright NK cells and progressively demethylated during maturation to CD56dim.
- Ascorbic acid treatment of CD56bright NK cells induced dose-dependent KIR expression and promoter demethylation.
- Ascorbic acid treatment enriched Runx3, TET2, and TET3 at KIR promoters.
- Overexpression of TET3 and Runx3 promoted KIR expression in CD56bright NK cells and NK-92 cells.
Conclusions:
- KIR promoter demethylation can be induced in immature CD56bright NK cells.
- Ascorbic acid facilitates KIR promoter demethylation and expression, potentially via TET enzymes and Runx3.
- This study elucidates a mechanism for controlling KIR expression during NK cell development.
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