Satellite cells (SCs) are stem cells responsible for post-hatch muscle growth through hypertrophy and in birds are sensitive to thermal stress during the first week after hatch. The mechanistic target of rapamycin (mTOR) signaling pathway, which is highly responsive to thermal stress in differentiating turkey pectoralis major (p. major) muscle SCs, regulates protein synthesis and the activities of SCs through a downstream effector, S6 kinase (S6K). The objectives of this study were: 1) to determine the effect of heat (43◦C) and cold (33◦C) stress on activity of the mTOR/S6K pathway in SCs isolated from the p. major muscle of one-week-old faster-growing modern commercial (NC) turkeys compared to those from slower-growing Randombred Control Line 2 (RBC2) turkeys, and 2) to assess the effect of mTOR knockdown on the proliferation, differentiation, and expression of myogenic regulatory factors of the SCs. Heat stress increased phosphorylation of both mTOR and S6K in both turkey lines, with greater increases observed in the RBC2 line. With cold stress, greater reductions in mTOR and S6K phosphorylation were observed in the NC line. Early knockdown of mTOR decreased proliferation, differentiation, and expression of myoblast determination protein 1 and myogenin in both lines independent of temperature, with the RBC2 line showing greater reductions in proliferation and differentiation than the NC line at 38◦ and 43◦C. Proliferating SCs are more dependent on mTOR/S6K-mediated regulation than differentiating SCs. Thus, thermal stress can affect breast muscle hypertrophic potential by changing satellite cell proliferation and differentiation, in part, through the mTOR/S6K pathway in a growth-dependent manner. These changes may result in irreversible effects on the development and growth of the turkey p. major muscle.
Bibliographical noteFunding Information:
This study was supported by the Agriculture and Food Research Initiative Competitive Grant No. 2020-67015-30827 from the United States Department of Agriculture to GMS, KMR, and SGV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
© 2022 Xu et al.
- Cell Differentiation/physiology
- Cell Proliferation/physiology
- Cold-Shock Response/physiology
- Heat-Shock Response/physiology
- Intracellular Signaling Peptides and Proteins/metabolism
- MyoD Protein/metabolism
- Protein Serine-Threonine Kinases/metabolism
- Ribosomal Protein S6 Kinases/metabolism
- Satellite Cells, Skeletal Muscle/metabolism
- TOR Serine-Threonine Kinases/metabolism
- Turkeys/growth & development
PubMed: MeSH publication types
- Research Support, Non-U.S. Gov't
- Journal Article