1. Rapamycin-sensitive signals control TCR/CD28-driven Ifng, Il4 and Foxp3 transcription and promoter region methylation.
- Author
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Tomasoni R, Basso V, Pilipow K, Sitia G, Saccani S, Agresti A, Mietton F, Natoli G, Colombetti S, and Mondino A
- Subjects
- Animals, CD4-Positive T-Lymphocytes metabolism, Cell Differentiation, Cells, Cultured, Cytokines metabolism, DNA Methylation, Forkhead Transcription Factors metabolism, GATA3 Transcription Factor biosynthesis, Interferon-gamma metabolism, Interleukin-2 biosynthesis, Interleukin-4 metabolism, Lymphocyte Activation, Mechanistic Target of Rapamycin Complex 1, Mice, Mice, Inbred BALB C, Multiprotein Complexes, Polymerase Chain Reaction, Promoter Regions, Genetic, Proteins metabolism, Signal Transduction, T-Box Domain Proteins biosynthesis, TOR Serine-Threonine Kinases metabolism, CD28 Antigens metabolism, CD4-Positive T-Lymphocytes immunology, Forkhead Transcription Factors genetics, Interferon-gamma genetics, Interleukin-4 genetics, Sirolimus pharmacology, Transcription, Genetic
- Abstract
The mammalian target of rapamycin (mTOR) controls T-cell differentiation in response to polarizing cytokines. We previously found that mTOR blockade by rapamycin (RAPA) delays the G1-S cell cycle transition and lymphocyte proliferation. Here, we report that both mTOR complex 1 and mTOR complex 2 are readily activated following TCR/CD28 engagement and are critical for early expression of Ifng, Il4 and Foxp3, and for effector T cell differentiation in the absence of polarizing cytokines. While inhibition of mTOR complex 1 and cell division were evident at low doses of RAPA, inhibition of mTOR complex 2, Ifng, Il4 and Foxp3 expression, and T-cell polarization required higher doses and more prolonged treatments. We found that while T-bet and GATA3 were readily induced following TCR/CD28 engagement, administration of RAPA delayed their expression, and interfered with the loss of DNA methylation within Ifng and Il4 promoter regions. In contrast, RAPA prevented activation-dependent DNA methylation of the Foxp3 promoter favoring Foxp3 expression. As a result, RAPA-cultured cells lacked immediate effector functions and instead were enriched for IL-2+ cells. We propose that mTOR-signaling, by timing the expression of critical transcription factors and DNA methylation of proximal promoter regions, regulates transcriptional competence at immunologically relevant sites and hence lymphocyte differentiation., (Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)
- Published
- 2011
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