Disruption of FOXP3-EZH2 Interaction Represents a Pathobiological Mechanism in Intestinal Inflammation. Cell Mol Gastroenterol Hepatol 2019;7(1):55-71
Date
12/05/2018Pubmed ID
30510991Pubmed Central ID
PMC6260395DOI
10.1016/j.jcmgh.2018.08.009Scopus ID
2-s2.0-85056879256 (requires institutional sign-in at Scopus site) 23 CitationsAbstract
BACKGROUND & AIMS: Forkhead box protein 3 (FOXP3)+ regulatory T cell (Treg) dysfunction is associated with autoimmune diseases; however, the mechanisms responsible for inflammatory bowel disease pathophysiology are poorly understood. Here, we tested the hypothesis that a physical interaction between transcription factor FOXP3 and the epigenetic enzyme enhancer of zeste homolog 2 (EZH2) is essential for gene co-repressive function.
METHODS: Human FOXP3 mutations clinically relevant to intestinal inflammation were generated by site-directed mutagenesis. T lymphocytes were isolated from mice, human blood, and lamina propria of Crohn's disease (CD) patients and non-CD controls. We performed proximity ligation or a co-immunoprecipitation assay in FOXP3-mutant+, interleukin 6 (IL6)-treated or CD-CD4+ T cells to assess FOXP3-EZH2 protein interaction. We studied IL2 promoter activity and chromatin state of the interferon γ locus via luciferase reporter and chromatin-immunoprecipitation assays, respectively, in cells expressing FOXP3 mutants.
RESULTS: EZH2 binding was abrogated by inflammatory bowel disease-associated FOXP3 cysteine 232 (C232) mutation. The C232 mutant showed impaired repression of IL2 and diminished EZH2-mediated trimethylation of histone 3 at lysine 27 on interferon γ, indicative of compromised Treg physiologic function. Generalizing this mechanism, IL6 impaired FOXP3-EZH2 interaction. IL6-induced effects were reversed by Janus kinase 1/2 inhibition. In lamina propria-derived CD4+T cells from CD patients, we observed decreased FOXP3-EZH2 interaction.
CONCLUSIONS: FOXP3-C232 mutation disrupts EZH2 recruitment and gene co-repressive function. The proinflammatory cytokine IL6 abrogates FOXP3-EZH2 interaction. Studies in lesion-derived CD4+ T cells have shown that reduced FOXP3-EZH2 interaction is a molecular feature of CD patients. Destabilized FOXP3-EZH2 protein interaction via diverse mechanisms and consequent Treg abnormality may drive gastrointestinal inflammation.
Author List
Bamidele AO, Svingen PA, Sagstetter MR, Sarmento OF, Gonzalez M, Braga Neto MB, Kugathasan S, Lomberk G, Urrutia RA, Faubion WA JrAuthors
Gwen Lomberk PhD Professor in the Surgery department at Medical College of WisconsinRaul A. Urrutia MD Center Director, Professor in the Surgery department at Medical College of Wisconsin
MESH terms used to index this publication - Major topics in bold
AdultAnimals
Cell Nucleus
Cell Separation
Co-Repressor Proteins
Enhancer of Zeste Homolog 2 Protein
Female
Forkhead Transcription Factors
Humans
Inflammation
Inflammatory Bowel Diseases
Interleukin-6
Intestines
Janus Kinases
Jurkat Cells
Male
Mice, Inbred C57BL
Middle Aged
Mutation
Phosphorylation
Phosphotyrosine
Polycomb Repressive Complex 2
Protein Binding
STAT3 Transcription Factor
Signal Transduction
T-Lymphocytes, Regulatory