Targeting microRNA-mediated gene repression limits adipogenic conversion of skeletal muscle mesenchymal stromal cells

Area of Science:

• Muscle biology
• Molecular genetics
• Cell differentiation

Background:

• Intramuscular fat accumulation impairs muscle function, particularly in muscular dystrophies and aging.
• Fibroadipogenic progenitors (FAPs) are mesenchymal stromal cells that differentiate into adipocytes, contributing to these detrimental fat deposits.

Purpose of the Study:

• To identify the molecular mechanisms controlling fibroadipogenic progenitor (FAP) differentiation into adipocytes.
• To investigate the role of microRNA-206 (miR-206) in regulating FAP fate and intramuscular adipogenesis.

Main Methods:

• Utilized mouse models with altered miR-206 expression to study adipogenesis following muscle injury.
• Employed labeled microRNA (miRNA) pull-down and sequencing (LAMP-seq) to identify direct targets of miR-206.
• Administered miR-206 mimics in vivo to assess their effect on intramuscular fat infiltration.

Main Results:

• Mice lacking miR-206 showed increased adipogenesis after muscle injury.
• miR-206 directly targets and represses the translation of the transcription factor Runx1.
• Absence of miR-206 led to increased Runx1 binding and expression of adipogenic genes in FAPs.
• In vivo miR-206 mimicry successfully reduced intramuscular fatty deposits.

Conclusions:

• miR-206 acts as a crucial molecular switch, inhibiting FAP differentiation into adipocytes by repressing Runx1.
• Understanding this miR-206/Runx1 axis provides novel insights into the pathogenesis of intramuscular fat accumulation.
• Targeting this pathway holds therapeutic potential for conditions characterized by excessive skeletal muscle fat infiltration.