Roquin Suppresses the PI3K-mTOR Signaling Pathway to Inhibit T Helper Cell Differentiation and Conversion of Treg to Tfr Cells

Essig, Katharina; Hu, Desheng; Guimaraes, Joao C.; Alterauge, Dominik; Edelmann, Stephanie; Raj, Timsse; Kranich, Jan; Behrens, Gesine; Heiseke, Alexander; Floess, Stefan; Klein, Juliane; Maiser, Andreas; Marschall, Susan; Hrabe de Angelis, Martin; Leonhardt, Heinrich; Calkhoven, Cornelis F.; Noessner, Elfriede; Brocker, Thomas; Huehn, Jochen; Krug, Anne B.; Zavolan, Mihaela; Baumjohann, Dirk; Heissmeyer, Vigo (2017): Roquin Suppresses the PI3K-mTOR Signaling Pathway to Inhibit T Helper Cell Differentiation and Conversion of Treg to Tfr Cells. In: Immunity, Vol. 47, No. 6: pp. 1067-1082

Abstract

Roquin proteins preclude spontaneous T cell activation and aberrant differentiation of T follicular helper (Tfh) or T helper 17 (Th17) cells. Here we showed that deletion of Roquin-encoding alleles specifically in regulatory T (Treg) cells also caused the activation of conventional T cells. Roquin-deficient Treg cells downregulated CD25, acquired a follicular Treg (Tfr) cell phenotype, and suppressed germinal center reactions but could not protect from colitis. Roquin inhibited the PI3K-mTOR signaling pathway by upregulation of Pten through interfering with miR-17 similar to 92 binding to an overlapping cis-element in the Pten 3' UTR, and downregulated the Foxo1-specific E3 ubiquitin ligase Itch. Loss of Roquin enhanced Akt-mTOR signaling and protein synthesis, whereas inhibition of PI3K or mTOR in Roquin-deficient T cells corrected enhanced Tfh and Th17 or reduced iTreg cell differentiation. Thereby, Roquin-mediated control of PI3K-mTOR signaling prevents autoimmunity by restraining activation and differentiation of conventional T cells and specialization of Treg cells.

• Item Type: Journal article
• Faculties: Medicine
• Research Centers: Center for Integrated Protein Science Munich (CIPSM)
• Subjects: 600 Technology > 610 Medicine and health; 500 Science > 540 Chemistry
• ISSN: 1074-7613
• Language: English