title: Rapamycin-sensitive signals control TCR/CD28-driven Ifng, Il4 and Foxp3 transcription and promoter region methylation.
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.
authors.affiliation: Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy.
authors.forename: Romana
authors.initials: R
authors.lastname: Tomasoni
authors.forename: Veronica
authors.initials: V
authors.lastname: Basso
authors.forename: Karolina
authors.initials: K
authors.lastname: Pilipow
authors.forename: Giovanni
authors.initials: G
authors.lastname: Sitia
authors.forename: Simona
authors.initials: S
authors.lastname: Saccani
authors.forename: Alessandra
authors.initials: A
authors.lastname: Agresti
authors.forename: Flore
authors.initials: F
authors.lastname: Mietton
authors.forename: Gioacchino
authors.initials: G
authors.lastname: Natoli
authors.forename: Sara
authors.initials: S
authors.lastname: Colombetti
authors.forename: Anna
authors.initials: A
authors.lastname: Mondino
mesh_terms: D000818:Animals; D018106:CD28 Antigens / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D002454:Cell Differentiation; D002478:Cells, Cultured; D016207:Cytokines / Q000378:metabolism; D019175:DNA Methylation; D051858:Forkhead Transcription Factors / Q000235:genetics* / Q000378:metabolism; D050990:GATA3 Transcription Factor / Q000096:biosynthesis; D007371:Interferon-gamma / Q000235:genetics* / Q000378:metabolism; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000235:genetics* / Q000378:metabolism; D008213:Lymphocyte Activation; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008807:Mice, Inbred BALB C; D046912:Multiprotein Complexes; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology*; D020825:T-Box Domain Proteins / Q000096:biosynthesis; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D014158:Transcription, Genetic; D000098815:T-bet Transcription Factor
chemical_list: D018106:CD28 Antigens; D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D050990:GATA3 Transcription Factor; C494748:Gata3 protein, mouse; D007376:Interleukin-2; D046912:Multiprotein Complexes; D011506:Proteins; D020825:T-Box Domain Proteins; D000098815:T-bet Transcription Factor; D015847:Interleukin-4; D007371:Interferon-gamma; C546843:mTOR protein, mouse; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases; D020123:Sirolimus