Mechanical Signaling Regulates DNA Methylation to Maintain Muscle Stem Cell Quiescence

Area of Science:

• Biomedical Engineering
• Cell Biology
• Epigenetics

Background:

• Skeletal muscle stem cells (MuSCs) maintain tissue regeneration by residing in a niche that integrates biophysical and biochemical signals.
• Maintaining stem cell quiescence is crucial for long-term tissue health and regenerative capacity.

Purpose of the Study:

• To investigate the role of substrate stiffness and RhoA signaling in regulating MuSC fate and epigenetic maintenance.
• To identify the downstream molecular mechanisms linking mechanical cues to stem cell quiescence.

Main Methods:

• Culturing MuSCs on matrices of varying stiffness.
• Utilizing RhoA depletion and Dnmt3a loss-of-function models.
• Analyzing cell morphology, actomyosin organization, DNA methylation landscape, gene expression, and alternative splicing.

Main Results:

• Soft matrices or RhoA depletion induced premature MuSC activation, altering cell morphology and actomyosin organization.
• Loss of RhoA signaling led to significant changes in DNA methylation, gene expression, and alternative splicing.
• Dnmt3a was downregulated upon RhoA loss and its depletion was sufficient to drive MuSC activation, identifying it as a key downstream effector.

Conclusions:

• A mechanotransduction-epigenetic axis involving RhoA and Dnmt3a maintains MuSC quiescence.
• RhoA signaling preserves stem cell quiescence by maintaining DNA methylation programs via Dnmt3a.
• This study defines a critical link between the mechanical niche and epigenetic regulation of stem cell fate.