Membrane-organizing protein moesin controls Treg differentiation and antitumor immunity via TGF-β signaling
Ephraim A. Ansa-Addo, … , Bei Liu, Zihai Li
Ephraim A. Ansa-Addo, … , Bei Liu, Zihai Li
Published April 3, 2017; First published March 13, 2017
Citation Information: J Clin Invest. 2017;127(4):1321-1337. https://doi.org/10.1172/JCI89281.
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Research Article Immunology

Membrane-organizing protein moesin controls Treg differentiation and antitumor immunity via TGF-β signaling

Abstract

Moesin is a member of the ezrin-radixin-moesin (ERM) family of proteins that are important for organizing membrane domains and receptor signaling and regulating the migration of effector T cells. Whether moesin plays any role during the generation of TGF-β–induced Tregs (iTregs) is unknown. Here, we have discovered that moesin is translationally regulated by TGF-β and is also required for optimal TGF-β signaling that promotes efficient development of iTregs. Loss of moesin impaired the development and function of both peripherally derived iTregs and in vitro–induced Tregs. Mechanistically, we identified an interaction between moesin and TGF-β receptor II (TβRII) that allows moesin to control the surface abundance and stability of TβRI and TβRII. We also found that moesin is required for iTreg conversion in the tumor microenvironment, and the deletion of moesin from recipient mice supported the rapid expansion of adoptively transferred CD8+ T cells against melanoma. Our study establishes moesin as an important regulator of the surface abundance and stability of TβRII and identifies moesin’s role in facilitating the efficient generation of iTregs. It also provides an advancement to our understanding about the role of the ERM proteins in regulating signal transduction pathways and suggests that modulation of moesin is a potential therapeutic target for Treg-related immune disorders.

Authors

Ephraim A. Ansa-Addo, Yongliang Zhang, Yi Yang, George S. Hussey, Breege V. Howley, Mohammad Salem, Brian Riesenberg, Shaoli Sun, Don C. Rockey, Serhan Karvar, Philip H. Howe, Bei Liu, Zihai Li

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Figure 1

TGF-β translationally upregulates moesin mRNA expression within iTregs.

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TGF-β translationally upregulates moesin mRNA expression within iTregs. ...
Primary CD4+CD25– T cells were isolated from C57BL/6 mice and stimulated with plate-bound anti-CD3 and soluble anti-CD28, IL-2, anti–IFN-γ, and anti–IL-4 without TGF-β for Th0 cells; or with IL-6 (50 ng/ml) and TGF-β (5 ng/ml) for Th17; and TGF-β1 (10 ng/ml) for iTregs for 3 days. (A) Immunoblotting of moesin, DAB2, and ILEI in T cells. (B–D) Fold mRNA of Msn (B), Dab2 (C), and Ilei (D) in Th0 and Th17 cells and iTregs. (E and F) Flow cytometry analysis (E) and immunoblot of FOXP3 expression (F) in iTregs using TGF-β1 or TGF-β2. (G and H) Polyribosome profiling (G) and RT-PCR (H) of Msn mRNA from monosomal fractions (40S, 60S, and 80S) in Th0 cells to the translating polysomal fractions in iTregs. (I and J) Quantitative RT-PCR of Msn (I) and Dab2 (J) mRNAs from the monosomal to polysomal fractions in iTregs. (K) Immunoblot of hnRNP E1, FOXP3, and β-actin in Th0 cells and iTregs. (L and M) RNA immunoprecipitation (RIP) of Msn and Ilei transcripts in Th0 cells and iTregs. Data represent the mean ± SD of 3 independent experiments performed in triplicate (B–D, I, and J), or 2 independent experiments performed in triplicate (L and M). *P < 0.05, **P < 0.01 by Student’s t test.