Thyroid hormone signaling is an essential regulator of skeletal muscle development, function, and metabolism, yet the specific signaling pathways required for muscle regeneration are not yet defined. We used scRNA-seq and the FUCCI (fluorescent ubiquitination-based cell cycle indicator) reporter mouse model to examine how hypothyroidism impacts repair processes after cardiotoxin-induced injury in mice. During regeneration, and up to 2 months after injury, hypothyroid muscles displayed smaller myofibers and a shift to slower oxidative fiber types. scRNA-seq of tibialis anterior muscle during regeneration revealed that hypothyroidism reduced myogenic-lineage diversity. Cell cycle analysis confirmed delayed cell cycle progression at 5 and 14 days after injury, with skeletal muscle stem cells stalled at the G1/S transition, hindering differentiation. Transcriptomic data revealed altered nonmyogenic dynamics, including elevated activated fibro-adipogenic progenitors (FAPs) early in repair and persistent proinflammatory macrophages. Integrative regulon and ligand-receptor analysis further demonstrated that triiodothyronine acted through dual modes: a direct transcriptional control of myogenic cell cycle and oxidative programs and an indirect paracrine remodeling mediated by FAP and immune signaling networks. This study identified what we believe to be novel effects of hypothyroidism on myogenic heterogeneity and impaired tissue repair, offering insights into muscle-wasting mechanisms relevant to hypothyroidism-associated myopathy and sarcopenia.
Paola Aguiari, Valentina Villani, Yan-Yun Liu, Gianni Carraro, Gregory A. Brent, Laura Perin, Anna Milanesi
Usage data is cumulative from March 2026 through August 2026.
| Usage | JCI | PMC |
|---|---|---|
| Text version | 2,264 | 0 |
| 487 | 0 | |
| Figure | 1,352 | 0 |
| Table | 141 | 0 |
| Supplemental data | 471 | 0 |
| Citation downloads | 334 | 0 |
| Totals | 5,049 | 0 |
| Total Views | 5,049 | |
Usage information is collected from two different sources: this site (JCI) and Pubmed Central (PMC). JCI information (compiled daily) shows human readership based on methods we employ to screen out robotic usage. PMC information (aggregated monthly) is also similarly screened of robotic usage.
Various methods are used to distinguish robotic usage. For example, Google automatically scans articles to add to its search index and identifies itself as robotic; other services might not clearly identify themselves as robotic, or they are new or unknown as robotic. Because this activity can be misinterpreted as human readership, data may be re-processed periodically to reflect an improved understanding of robotic activity. Because of these factors, readers should consider usage information illustrative but subject to change.