Mechanical input restrains PPARγ2 expression and action to preserve mesenchymal stem cell multipotentiality

Area of Science:

• Biomedical Engineering
• Cell Biology
• Stem Cell Research

Background:

• Mechanical signals from exercise promote bone formation and inhibit fat cell differentiation.
• Previous studies suggest mechanical signals activate β-catenin and limit PPARγ2 expression to block adipogenesis.
• The role of mechanical signals in inhibiting adipogenesis during PPARγ transactivation remains unclear.

Purpose of the Study:

• To investigate how mechanical signals limit adipogenesis in marrow-derived mesenchymal stem cells (mdMSC) after PPARγ activation.
• To determine if mechanical strain can prevent adipogenesis by affecting PPARγ expression and function.
• To assess the impact of mechanical strain on the multipotency of mdMSC.

Main Methods:

• mdMSC were treated with rosiglitazone to induce adipogenesis and subjected to mechanical strain.
• Overexpression of PPARγ2 was used to test the necessity of PPARγ downregulation for anti-adipogenic effects.
• AP2-GFP reporter mice were used to track adipogenic differentiation and assess the multipotency of specific cell fractions under mechanical strain.

Main Results:

• Mechanical strain inhibited rosiglitazone-induced adipogenesis, preventing PPARγ upregulation and key adipogenic protein expression.
• Even with PPARγ2 overexpression, mechanical strain and GSK3β inhibition blocked adipogenic protein production.
• Mechanical strain reduced the proportion of terminally differentiated adipocytes, preserving the multipotency of mdMSC.

Conclusions:

• Mechanical strain restricts adipogenesis by both limiting PPARγ2 expression and interfering with PPARγ action.
• Mechanical signals protect the multipotent state of mesenchymal stem cells, favoring osteogenesis over adipogenesis.
• These findings highlight the potential of mechanical interventions to modulate stem cell fate for therapeutic benefit.