Type 2 deiodinase–dependent surge in thyroid hormone controls muscle stem cell quiescence and self-renewal
Maria Angela De Stefano, Raffaele Ambrosio, Cristina Luongo, Tommaso Porcelli, Daniela Di Girolamo, Caterina Miro, Monica Dentice, Caterina Missero, Domenico Salvatore
Maria Angela De Stefano, Raffaele Ambrosio, Cristina Luongo, Tommaso Porcelli, Daniela Di Girolamo, Caterina Miro, Monica Dentice, Caterina Missero, Domenico Salvatore
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Research Article Endocrinology Metabolism

Type 2 deiodinase–dependent surge in thyroid hormone controls muscle stem cell quiescence and self-renewal

Abstract

Stem cells are critical for the homeostasis of adult tissues. Thyroid hormone (TH), whose intracellular concentration is increased by type 2 deiodinase (D2), is involved in many functions, but its role in quiescence is unknown. Here, we show that D2 marks quiescent stem cells in muscle and skin. Genetic D2 depletion in quiescent muscle stem cells triggered their transition from a G0 to a GAlert-like state. This increased the proliferative potential of the stem cells but impaired their self-renewal capacity, leading to depletion of the stem cell pool and regenerative failure over time. Mechanistically, TH sustained Notch signaling, and active Notch overexpression partially rescued D2 depletion. Transient pharmacological inhibition of D2 accelerated muscle regeneration and skin wound healing by promoting stem cell expansion. In conclusion, we show that D2 is a critical metabolic enzyme in maintaining stem cell quiescence and in regulating self-renewal.

Authors

Maria Angela De Stefano, Raffaele Ambrosio, Cristina Luongo, Tommaso Porcelli, Daniela Di Girolamo, Caterina Miro, Monica Dentice, Caterina Missero, Domenico Salvatore

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Figure 4

D2 action sustains the Notch signaling pathway.

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D2 action sustains the Notch signaling pathway. (A) Volcano plot showing...
(A) Volcano plot showing differences in the mRNA expression of qMuSCs from cD2KO and WT mice. Negative log10 P value (y axis) and log2 fold change (x axis) are plotted for transcripts detected by RNA-seq analysis. The experiments were conducted on n = 3 biological replicates. Gray line indicates P value < 0.05. (B) The top upregulated pathways in Panther (Protein Analysis Through Evolutionary Relationships; http://www.pantherdb.org/). (C) The downregulated pathways in Panther. (D) mRNA levels of Notch receptors (Notch1–4) and Notch targets (HeyL, Hes2, and Rbpi) in freshly isolated qMuSCs by FACS. n = 6 WT and n = 6 cD2KO mice. (E) Western blot of cD2KO and WT qMuSCs freshly isolated by FACS. The graph on the right shows the quantification of N1ICD/tubulin. (F and G) ChIP-qPCR using THR-α and isotype IgG control antibodies on proximal enhancer and promoter regions of Notch2 and Notch3 genes, respectively, in C2C12 cells. Data are normalized to input chromatin; n = 3 biologically independent samples. (H) ChIP-qPCR using THR-α and isotype IgG control antibodies on proximal enhancer of Notch2 in freshly isolated MuSCs from WT, rT3-treated, and D2KO cells. Data are normalized to input chromatin; n = 3 biologically independent samples. (I) Mouse model used and diagram of in vivo rescue experiment. 2 independent experiments were conducted with n = 4 WT, n = 4 cD2KO, and n = 4 cD2KO-N1ICD mice each. (J) Representative IF of PAX7 (red) and MyoD (green) in TA muscle from indicated mice harvested 21 days after CTX injection. Scale bars: 50 μm. (K) The number of PAX7–MyoD+, PAX7+MyoD+, and PAX7+MyoD– cells per mm2. Bars represent the average of at least 3 technical replicates. n = 8 mice for each group. Data are presented as mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 using a 2-tailed Student’s t test when comparing 2 conditions and 2-way ANOVA when comparing multiple conditions.