Critical roles of mTOR Complex 1 and 2 for T follicular helper cell differentiation and germinal center responses.

Yang, Jialong; Lin, Xingguang; Pan, Yun; Wang, Jinli; Chen, Pengcheng; Huang, Hongxiang; Xue, Hai-Hui; Gao, Jimin et al. · Elife · 2016

basic_science · Level V

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Abstract

T follicular helper (Tfh) cells play critical roles for germinal center responses and effective humoral immunity. We report here that mTOR in CD4 T cells is essential for Tfh differentiation. In <i>Mtor<sup>f/f</sup>-Cd4Cre</i> mice, both constitutive and inducible Tfh differentiation is severely impaired, leading to defective germinal center B cell formation and antibody production. Moreover, both mTORC1 and mTORC2 contribute to Tfh and GC B cell development but may do so via distinct mechanisms. mTORC1 mainly promotes CD4 T cell proliferation to reach the cell divisions necessary for Tfh differentiation, while Rictor/mTORC2 regulates Tfh differentiation by promoting Akt activation and TCF1 expression without grossly influencing T cell proliferation. Together, our results reveal crucial but distinct roles for mTORC1 and mTORC2 in CD4 T cells during Tfh differentiation and germinal center responses.

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