miR-199b-5p enhances the proliferation of medullary thymic epithelial cells via regulating Wnt signaling by targeting Fzd6.

Xintong Wang, Ying Li, Bishuang Gong, Kaizhao Zhang, Yongjiang Ma, Yugu Li

Acta biochimica et biophysica Sinica 2021 Jan 12

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Thymic epithelial cells (TECs) are essential regulators of T-cell development and selection. miRNAs play critical roles in regulating TEC proliferation during the process of thymic aging. Our previous studies revealed that miR-199b-5p was upregulated in TECs from 1- to 3-month-old mice. But its function and potential mechanism are not clear. We hypothesized that miR-199b-5p may play an important role in age-related thymus involution via targeting some genes. To confirm it, the murine thymic epithelial cell line 1 (MTEC1) cells were used. Our results showed that overexpression of miR-199b-5p can enhance MTEC1 cell proliferation. On the contrary, repression of miR-199b-5p can inhibit MTEC1 cell proliferation. Meanwhile, it was confirmed that frizzled receptor 6 (Fzd6) is the direct target gene of miR-199b-5p. Furthermore, overexpression of miR-199b-5p can upregulate the expressions of β-catenin, Tcf7, Wnt4, and C-myc to activate Wnt signaling and cell cycle signaling. Silence of Fzd6 and co-transfection with siFzd6 and miR-199b-5p mimic/inhibitor confirmed that the biological function of miR-199b-5p is indeed by targeting Fzd6 in medullary TECs. Overall, miR-199b-5p is an important regulator in medullary TEC proliferation through targeting Fzd6 to activate Wnt signaling and cell cycle signaling. Our data indicate that miR-199b-5p may block the process of thymic aging and be a potential therapeutic target for thymus involution. © The Author(s) 2021. Published by Oxford University Press on behalf of the Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Citation

Xintong Wang, Ying Li, Bishuang Gong, Kaizhao Zhang, Yongjiang Ma, Yugu Li. miR-199b-5p enhances the proliferation of medullary thymic epithelial cells via regulating Wnt signaling by targeting Fzd6. Acta biochimica et biophysica Sinica. 2021 Jan 12;53(1):36-45