Methyltransferase G9A regulates T cell differentiation during murine intestinal inflammation
Frann Antignano, … , Megan K. Levings, Colby Zaph
Frann Antignano, … , Megan K. Levings, Colby Zaph
Published March 25, 2014
Citation Information: J Clin Invest. 2014;124(5):1945-1955. https://doi.org/10.1172/JCI69592.
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Methyltransferase G9A regulates T cell differentiation during murine intestinal inflammation

Abstract

Inflammatory bowel disease (IBD) pathogenesis is associated with dysregulated CD4+ Th cell responses, with intestinal homeostasis depending on the balance between IL-17–producing Th17 and Foxp3+ Tregs. Differentiation of naive T cells into Th17 and Treg subsets is associated with specific gene expression profiles; however, the contribution of epigenetic mechanisms to controlling Th17 and Treg differentiation remains unclear. Using a murine T cell transfer model of colitis, we found that T cell–intrinsic expression of the histone lysine methyltransferase G9A was required for development of pathogenic T cells and intestinal inflammation. G9A-mediated dimethylation of histone H3 lysine 9 (H3K9me2) restricted Th17 and Treg differentiation in vitro and in vivo. H3K9me2 was found at high levels in naive Th cells and was lost following Th cell activation. Loss of G9A in naive T cells was associated with increased chromatin accessibility and heightened sensitivity to TGF-β1. Pharmacological inhibition of G9A methyltransferase activity in WT T cells promoted Th17 and Treg differentiation. Our data indicate that G9A-dependent H3K9me2 is a homeostatic epigenetic checkpoint that regulates Th17 and Treg responses by limiting chromatin accessibility and TGF-β1 responsiveness, suggesting G9A as a therapeutic target for treating intestinal inflammation.

Authors

Frann Antignano, Kyle Burrows, Michael R. Hughes, Jonathan M. Han, Ken J. Kron, Nadia M. Penrod, Menno J. Oudhoff, Steven Kai Hao Wang, Paul H. Min, Matthew J. Gold, Alistair L. Chenery, Mitchell J.S. Braam, Thomas C. Fung, Fabio M.V. Rossi, Kelly M. McNagny, Cheryl H. Arrowsmith, Mathieu Lupien, Megan K. Levings, Colby Zaph

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Figure 2

Expansion of Foxp3+ Tregs after transfer of naive G9a–/– Th cells into Rag1–/– mice.

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Expansion of Foxp3+ Tregs after transfer of naive G9a–/– Th cells into R...
CD4+CD25–CD45RBhi naive T cells (4 × 105) from G9afl/fl or G9a–/– mice were transferred into Rag1–/– mice. (A) The frequency of Tregs (CD4+CD25+Foxp3+) in peripheral blood of Rag1–/– mice that received G9afl/fl or G9a–/– T cells was quantified by flow cytometry. (B) Representative CD25 and Foxp3 staining of peripheral blood CD4+ cells at 7 weeks after transfer. Numbers represent frequency of CD4+CD25+Foxp3+ cells. (C) Representative CD4 and Foxp3 staining and (D) quantitative analysis of the frequency and total number of Foxp3+ cells from the spleen, mLN, and LP from Rag1–/– mice receiving G9afl/fl or G9a–/– naive T cells. Data are from 1 representative experiment of 4 experiments (n = 5–8 per experiment). Numbers represent frequency of CD4+Foxp3+ cells. (E) Cells from the spleen, mLN, and LP of G9afl/fl or G9a–/– mice were stained for CD4 and these cells analyzed for expression of CD25 and intracellular Foxp3. Representative FACS plots are shown (n = 3–6). Numbers represent frequency of CD4+CD25+Foxp3+ cells. (F) Proliferation of bead-sorted CD4+CD25– Teff cells from WT mice cultured alone or with the indicated ratios of G9afl/fl or G9a–/– CD4+CD25+ Tregs in the presence of T cell activator beads for 4 days. Data are representative of 3 independent experiments. **P < 0.01; ***P < 0.001. Error bars indicate SEM.