Targeted mRNA Decay by RNA Binding Protein AUF1 Regulates Adult Muscle Stem Cell Fate, Promoting Skeletal Muscle Integrity

• AUF1 regulates muscle stem cell function by targeted degradation of specific mRNAs
• auf1−/− mice undergo skeletal muscle wasting and impaired regeneration following injury
• AUF1 control of mRNA decay is a mechanism for regulating tissue regeneration
• Mutations in AUF1 are implicated in human muscle-wasting diseases

SummaryFollowing skeletal muscle injury, muscle stem cells (satellite cells) are activated, proliferate, and differentiate to form myofibers. We show that mRNA-decay protein AUF1 regulates satellite cell function through targeted degradation of specific mRNAs containing 3′ AU-rich elements (AREs). auf1−/− mice undergo accelerated skeletal muscle wasting with age and impaired skeletal muscle repair following injury. Satellite cell mRNA analysis and regeneration studies demonstrate that auf1−/− satellite cell self-renewal is impaired due to increased stability and overexpression of ARE-mRNAs, including cell-autonomous overexpression of matrix metalloprotease MMP9. Secreted MMP9 degrades the skeletal muscle matrix, preventing satellite-cell-mediated regeneration and return to quiescence. Blocking MMP9 activity in auf1−/− mice restores skeletal muscle repair and maintenance of the satellite cell population. Control of ARE-mRNA decay by AUF1 represents a mechanism for adult stem cell regulation and is implicated in human skeletal muscle wasting diseases.

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