PAX3 Confers Functional Heterogeneity in Skeletal Muscle Stem Cell Responses to Environmental Stress

Area of Science:

• Muscle stem cell biology
• Environmental toxicology
• Molecular genetics

Background:

• Adult skeletal muscle repair relies on quiescent muscle satellite cells (MuSCs).
• The effects of environmental stressors, such as pollution, on MuSC behavior are largely unknown.
• 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is a widespread and highly toxic environmental pollutant.

Purpose of the Study:

• To investigate the impact of TCDD exposure on MuSC behavior.
• To identify specific MuSC subpopulations and their responses to environmental stress.
• To elucidate the molecular mechanisms underlying MuSC stress resistance.

Main Methods:

• Utilized in vivo mouse molecular genetic models.
• Performed ex vivo studies on MuSCs.
• Analyzed gene expression, cell survival, activation, and differentiation markers.

Main Results:

• MuSCs exhibit functional heterogeneity, with a subset expressing PAX3 showing stress resistance.
• TCDD exposure impairs survival and alters activation/differentiation of PAX3-negative MuSCs via aryl hydrocarbon receptor signaling.
• Impaired PAX3 function sensitizes MuSCs to stress, highlighting the protective role of PAX3-mediated mTORC1 induction.

Conclusions:

• PAX3 defines a subpopulation of MuSCs resistant to environmental stress.
• PAX3-mediated mTORC1 signaling is critical for MuSC protection against pollutants.
• Functional heterogeneity in MuSCs is a key factor in responding to environmental challenges.