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1.  Deletion of a Conserved cis-Element in the Ifng Locus Highlights the Role of Acute Histone Acetylation in Modulating Inducible Gene Transcription 
PLoS Genetics  2014;10(1):e1003969.
Differentiation-dependent regulation of the Ifng cytokine gene locus in T helper (Th) cells has emerged as an excellent model for functional study of distal elements that control lineage-specific gene expression. We previously identified a cis-regulatory element located 22 kb upstream of the Ifng gene (Conserved Non-coding Sequence -22, or CNS-22) that is a site for recruitment of the transcription factors T-bet, Runx3, NF-κB and STAT4, which act to regulate transcription of the Ifng gene in Th1 cells. Here, we report the generation of mice with a conditional deletion of CNS-22 that has enabled us to define the epigenetic and functional consequences of its absence. Deletion of CNS-22 led to a defect in induction of Ifng by the cytokines IL-12 and IL-18, with a more modest effect on induction via T-cell receptor activation. To better understand how CNS-22 and other Ifng CNSs regulated Ifng transcription in response to these distinct stimuli, we examined activation-dependent changes in epigenetic modifications across the extended Ifng locus in CNS-22-deficient T cells. We demonstrate that in response to both cytokine and TCR driven activation signals, CNS-22 and other Ifng CNSs recruit increased activity of histone acetyl transferases (HATs) that transiently enhance levels of histones H3 and H4 acetylation across the extended Ifng locus. We also demonstrate that activation-responsive increases in histone acetylation levels are directly linked to the ability of Ifng CNSs to acutely enhance Pol II recruitment to the Ifng promoter. Finally, we show that impairment in IL-12+IL-18 dependent induction of Ifng stems from the importance of CNS-22 in coordinating locus-wide levels of histone acetylation in response to these cytokines. These findings identify a role for acute histone acetylation in the enhancer function of distal conserved cis-elements that regulate of Ifng gene expression.
Author Summary
Differentiation of multipotent naïve T cell precursors into functionally mature effector cells that control different types of immune responses is an excellent model to study lineage-specific regulation of gene expression. A number of cis-regulatory elements have been reported to control expression of the gene that encodes the cytokine IFN-γ which is a signature product of effector T cells of the Th1 lineage. However, none of these elements has been analyzed for effects on gene expression and chromatin remodeling through deletional analysis in the native Ifng gene locus. Here we have generated mice in which a key element previously implicated in control of Ifng gene expression (CNS-22) was conditionally deleted from the genome. Th1 cells in which CNS-22 was deleted had activation-specific deficits in Ifng expression and demonstrated defects in epigenetic changes across the Ifng locus. Mapping epigenetic consequences of CNS-22 deletion led to identification of acute hyperacetylation of histones immediately flanking this and other cis-regulatory elements that was associated with Ifng gene transcription, as well as more global defects in histone acetylation. These findings support a mechanism whereby regulatory sites that have acquired baseline histone acetylation marks during lineage specification undergo acute, activation-dependent increases in histone acetyl transferase activity that enhance transcription of inducible genes.
PMCID: PMC3886902  PMID: 24415943
2.  Late Developmental Plasticity in the T Helper 17 Lineage 
Immunity  2009;30(1):92-107.
Development of T helper (Th) 17 cells requires transforming growth factor (TGF)-β and interleukin (IL)-6 and is independent of the Th1 pathway. Although T cells that produce interferon (IFN)-γ are a recognized feature of Th17 cell responses, mice deficient for STAT4 and T-bet—two prototypical Th1 transcription factors—are protected from autoimmunity associated with Th17 pathogenesis. To examine the fate and pathogenic potential of Th17 cells and origin of IFN-γ-producing T cells that emerge during Th17 immunity, we developed IL-17F reporter mice that identify cells committed to expression of IL-17F and IL-17A. Th17 cells required TGF-β for sustained expression of IL-17F and IL-17A. In the absence of TGF-β, both IL-23 and IL-12 acted to suppress IL-17 and enhance IFN-γ production in a STAT4- and T-bet-dependent manner, albeit with distinct efficiencies. These results support a model of late Th17 developmental plasticity with implications for auto-immunity and host defense.
PMCID: PMC3607320  PMID: 19119024
3.  IL-9 as a mediator of Th17-driven inflammatory disease 
The Journal of Experimental Medicine  2009;206(8):1653-1660.
We report that like other T cells cultured in the presence of transforming growth factor (TGF) β, Th17 cells also produce interleukin (IL) 9. Th17 cells generated in vitro with IL-6 and TGF-β as well as purified ex vivo Th17 cells both produced IL-9. To determine if IL-9 has functional consequences in Th17-mediated inflammatory disease, we evaluated the role of IL-9 in the development and progression of experimental autoimmune encephalomyelitis, a mouse model of multiple sclerosis. The data show that IL-9 neutralization and IL-9 receptor deficiency attenuates disease, and this correlates with decreases in Th17 cells and IL-6–producing macrophages in the central nervous system, as well as mast cell numbers in the regional lymph nodes. Collectively, these data implicate IL-9 as a Th17-derived cytokine that can contribute to inflammatory disease.
PMCID: PMC2722185  PMID: 19596803

Results 1-3 (3)