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 5

D2 depletion turns qMuSCs to an alert state.

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D2 depletion turns qMuSCs to an alert state. (A) Schematic of the experi...
(A) Schematic of the experiment. (B) Representative FACS plots for EdU/Pax7-GFP of MuSCs isolated from resting TA muscle of indicated mice (upper panels) and from alerted and injured muscles of WT mice (lower panels). (C) Percentage of EdU+/MuSCs in B. n = 4 independent experiments with n = 3 WT and cD2KO mice. (D and E) Representative IF of PAX7 and p-mTOR (D) and p-S6 (E) in FACS-isolated MuSCs from resting WT and cD2KO mice (scale bars: 200 μm) and respective quantification of the percentage of PAX7+p-mTOR+ cells (D) and PAX7+p-S6+ cells (E). n = 8 WT and n = 8 cD2KO mice. (F and G) Western blots of p-S6K and total S6K (F) and p-AMPK and total AMPK (G). Tubulin and ERK served as a loading control. (H) Relative content of mtDNA in FACS-isolated MuSCs from resting WT, resting cD2KO, alerted WT, and injured WT mice muscles. n = 6 WT and cD2KO mice. (I) Representative FACS histogram of forward scatter (FSC) signal of MuSCs from resting WT (light blue), resting cD2KO (green), and injured WT (blue) muscles. (J) Dio2 mRNA levels of MuSCs from WT muscles in resting (Ctr) and alerted conditions. Alerted MuSCs were harvested 2 days after CTX in contralateral TA muscle. n = 8 WT and cD2KO mice. (K) Venn comparison analysis between cD2KO RNA-seq and GAlert state array (10); common genes downregulated (P < 2.418 × 10–16) and common genes upregulated (P < 0.041) are shown. (L) Heatmap comparison of common genes up/downregulated from cD2KO RNA-seq versus control (quiescent) and GAlert state array previously described (10). Data are presented as mean ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 using a Mann-Whitney test when comparing 2 conditions, and 2-way ANOVA when comparing multiple conditions.